quic/core/quic_connection_test.cc - quiche - Git at Google

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.

 #include "net/third_party/quiche/src/quic/core/quic_connection.h"

 #include <errno.h>

 #include <memory>
 #include <ostream>
 #include <string>
 #include <utility>

 #include "net/third_party/quiche/src/quic/core/congestion_control/loss_detection_interface.h"
 #include "net/third_party/quiche/src/quic/core/congestion_control/send_algorithm_interface.h"
 #include "net/third_party/quiche/src/quic/core/crypto/null_decrypter.h"
 #include "net/third_party/quiche/src/quic/core/crypto/null_encrypter.h"
 #include "net/third_party/quiche/src/quic/core/crypto/quic_decrypter.h"
 #include "net/third_party/quiche/src/quic/core/crypto/quic_encrypter.h"
 #include "net/third_party/quiche/src/quic/core/quic_connection_id.h"
 #include "net/third_party/quiche/src/quic/core/quic_packets.h"
 #include "net/third_party/quiche/src/quic/core/quic_simple_buffer_allocator.h"
 #include "net/third_party/quiche/src/quic/core/quic_types.h"
 #include "net/third_party/quiche/src/quic/core/quic_utils.h"
 #include "net/third_party/quiche/src/quic/platform/api/quic_error_code_wrappers.h"
 #include "net/third_party/quiche/src/quic/platform/api/quic_expect_bug.h"
 #include "net/third_party/quiche/src/quic/platform/api/quic_flags.h"
 #include "net/third_party/quiche/src/quic/platform/api/quic_logging.h"
 #include "net/third_party/quiche/src/quic/platform/api/quic_reference_counted.h"
 #include "net/third_party/quiche/src/quic/platform/api/quic_str_cat.h"
 #include "net/third_party/quiche/src/quic/platform/api/quic_string_piece.h"
 #include "net/third_party/quiche/src/quic/platform/api/quic_test.h"
 #include "net/third_party/quiche/src/quic/test_tools/mock_clock.h"
 #include "net/third_party/quiche/src/quic/test_tools/mock_random.h"
 #include "net/third_party/quiche/src/quic/test_tools/quic_config_peer.h"
 #include "net/third_party/quiche/src/quic/test_tools/quic_connection_peer.h"
 #include "net/third_party/quiche/src/quic/test_tools/quic_framer_peer.h"
 #include "net/third_party/quiche/src/quic/test_tools/quic_packet_creator_peer.h"
 #include "net/third_party/quiche/src/quic/test_tools/quic_packet_generator_peer.h"
 #include "net/third_party/quiche/src/quic/test_tools/quic_sent_packet_manager_peer.h"
 #include "net/third_party/quiche/src/quic/test_tools/quic_test_utils.h"
 #include "net/third_party/quiche/src/quic/test_tools/simple_data_producer.h"
 #include "net/third_party/quiche/src/quic/test_tools/simple_quic_framer.h"
 #include "net/third_party/quiche/src/quic/test_tools/simple_session_notifier.h"

 using testing::_;
 using testing::AnyNumber;
 using testing::AtLeast;
 using testing::DoAll;
 using testing::Exactly;
 using testing::Ge;
 using testing::IgnoreResult;
 using testing::InSequence;
 using testing::Invoke;
 using testing::InvokeWithoutArgs;
 using testing::Lt;
 using testing::Ref;
 using testing::Return;
 using testing::SaveArg;
 using testing::SetArgPointee;
 using testing::StrictMock;

 namespace quic {
 namespace test {
 namespace {

 const char data1[] = "foo data";
 const char data2[] = "bar data";

 const bool kHasStopWaiting = true;

 const int kDefaultRetransmissionTimeMs = 500;

 DiversificationNonce kTestDiversificationNonce = {
     'a', 'b', 'a', 'b', 'a', 'b', 'a', 'b', 'a', 'b', 'a',
     'b', 'a', 'b', 'a', 'b', 'a', 'b', 'a', 'b', 'a', 'b',
     'a', 'b', 'a', 'b', 'a', 'b', 'a', 'b', 'a', 'b',
 };

 const QuicSocketAddress kPeerAddress =
     QuicSocketAddress(QuicIpAddress::Loopback6(),
                       /*port=*/12345);
 const QuicSocketAddress kSelfAddress =
     QuicSocketAddress(QuicIpAddress::Loopback6(),
                       /*port=*/443);

 QuicStreamId GetNthClientInitiatedStreamId(int n,
                                            QuicTransportVersion version) {
   return QuicUtils::GetFirstBidirectionalStreamId(version,
                                                   Perspective::IS_CLIENT) +
          n * 2;
 }

 QuicLongHeaderType EncryptionlevelToLongHeaderType(EncryptionLevel level) {
   switch (level) {
     case ENCRYPTION_INITIAL:
       return INITIAL;
     case ENCRYPTION_HANDSHAKE:
       return HANDSHAKE;
     case ENCRYPTION_ZERO_RTT:
       return ZERO_RTT_PROTECTED;
     case ENCRYPTION_FORWARD_SECURE:
       DCHECK(false);
       return INVALID_PACKET_TYPE;
     default:
       DCHECK(false);
       return INVALID_PACKET_TYPE;
   }
 }

 // TaggingEncrypter appends kTagSize bytes of |tag| to the end of each message.
 class TaggingEncrypter : public QuicEncrypter {
  public:
   explicit TaggingEncrypter(uint8_t tag) : tag_(tag) {}
   TaggingEncrypter(const TaggingEncrypter&) = delete;
   TaggingEncrypter& operator=(const TaggingEncrypter&) = delete;

   ~TaggingEncrypter() override {}

   // QuicEncrypter interface.
   bool SetKey(QuicStringPiece /*key*/) override { return true; }

   bool SetNoncePrefix(QuicStringPiece /*nonce_prefix*/) override {
     return true;
   }

   bool SetIV(QuicStringPiece /*iv*/) override { return true; }

   bool SetHeaderProtectionKey(QuicStringPiece /*key*/) override { return true; }

   bool EncryptPacket(uint64_t /*packet_number*/,
                      QuicStringPiece /*associated_data*/,
                      QuicStringPiece plaintext,
                      char* output,
                      size_t* output_length,
                      size_t max_output_length) override {
     const size_t len = plaintext.size() + kTagSize;
     if (max_output_length < len) {
       return false;
     }
     // Memmove is safe for inplace encryption.
     memmove(output, plaintext.data(), plaintext.size());
     output += plaintext.size();
     memset(output, tag_, kTagSize);
     *output_length = len;
     return true;
   }

   std::string GenerateHeaderProtectionMask(
       QuicStringPiece /*sample*/) override {
     return std::string(5, 0);
   }

   size_t GetKeySize() const override { return 0; }
   size_t GetNoncePrefixSize() const override { return 0; }
   size_t GetIVSize() const override { return 0; }

   size_t GetMaxPlaintextSize(size_t ciphertext_size) const override {
     return ciphertext_size - kTagSize;
   }

   size_t GetCiphertextSize(size_t plaintext_size) const override {
     return plaintext_size + kTagSize;
   }

   QuicStringPiece GetKey() const override { return QuicStringPiece(); }

   QuicStringPiece GetNoncePrefix() const override { return QuicStringPiece(); }

  private:
   enum {
     kTagSize = 12,
   };

   const uint8_t tag_;
 };

 // TaggingDecrypter ensures that the final kTagSize bytes of the message all
 // have the same value and then removes them.
 class TaggingDecrypter : public QuicDecrypter {
  public:
   ~TaggingDecrypter() override {}

   // QuicDecrypter interface
   bool SetKey(QuicStringPiece /*key*/) override { return true; }

   bool SetNoncePrefix(QuicStringPiece /*nonce_prefix*/) override {
     return true;
   }

   bool SetIV(QuicStringPiece /*iv*/) override { return true; }

   bool SetHeaderProtectionKey(QuicStringPiece /*key*/) override { return true; }

   bool SetPreliminaryKey(QuicStringPiece /*key*/) override {
     QUIC_BUG << "should not be called";
     return false;
   }

   bool SetDiversificationNonce(const DiversificationNonce& /*key*/) override {
     return true;
   }

   bool DecryptPacket(uint64_t /*packet_number*/,
                      QuicStringPiece /*associated_data*/,
                      QuicStringPiece ciphertext,
                      char* output,
                      size_t* output_length,
                      size_t /*max_output_length*/) override {
     if (ciphertext.size() < kTagSize) {
       return false;
     }
     if (!CheckTag(ciphertext, GetTag(ciphertext))) {
       return false;
     }
     *output_length = ciphertext.size() - kTagSize;
     memcpy(output, ciphertext.data(), *output_length);
     return true;
   }

   std::string GenerateHeaderProtectionMask(
       QuicDataReader* /*sample_reader*/) override {
     return std::string(5, 0);
   }

   size_t GetKeySize() const override { return 0; }
   size_t GetNoncePrefixSize() const override { return 0; }
   size_t GetIVSize() const override { return 0; }
   QuicStringPiece GetKey() const override { return QuicStringPiece(); }
   QuicStringPiece GetNoncePrefix() const override { return QuicStringPiece(); }
   // Use a distinct value starting with 0xFFFFFF, which is never used by TLS.
   uint32_t cipher_id() const override { return 0xFFFFFFF0; }

  protected:
   virtual uint8_t GetTag(QuicStringPiece ciphertext) {
     return ciphertext.data()[ciphertext.size() - 1];
   }

  private:
   enum {
     kTagSize = 12,
   };

   bool CheckTag(QuicStringPiece ciphertext, uint8_t tag) {
     for (size_t i = ciphertext.size() - kTagSize; i < ciphertext.size(); i++) {
       if (ciphertext.data()[i] != tag) {
         return false;
       }
     }

     return true;
   }
 };

 // StringTaggingDecrypter ensures that the final kTagSize bytes of the message
 // match the expected value.
 class StrictTaggingDecrypter : public TaggingDecrypter {
  public:
   explicit StrictTaggingDecrypter(uint8_t tag) : tag_(tag) {}
   ~StrictTaggingDecrypter() override {}

   // TaggingQuicDecrypter
   uint8_t GetTag(QuicStringPiece /*ciphertext*/) override { return tag_; }

   // Use a distinct value starting with 0xFFFFFF, which is never used by TLS.
   uint32_t cipher_id() const override { return 0xFFFFFFF1; }

  private:
   const uint8_t tag_;
 };

 class TestConnectionHelper : public QuicConnectionHelperInterface {
  public:
   TestConnectionHelper(MockClock* clock, MockRandom* random_generator)
       : clock_(clock), random_generator_(random_generator) {
     clock_->AdvanceTime(QuicTime::Delta::FromSeconds(1));
   }
   TestConnectionHelper(const TestConnectionHelper&) = delete;
   TestConnectionHelper& operator=(const TestConnectionHelper&) = delete;

   // QuicConnectionHelperInterface
   const QuicClock* GetClock() const override { return clock_; }

   QuicRandom* GetRandomGenerator() override { return random_generator_; }

   QuicBufferAllocator* GetStreamSendBufferAllocator() override {
     return &buffer_allocator_;
   }

  private:
   MockClock* clock_;
   MockRandom* random_generator_;
   SimpleBufferAllocator buffer_allocator_;
 };

 class TestAlarmFactory : public QuicAlarmFactory {
  public:
   class TestAlarm : public QuicAlarm {
    public:
     explicit TestAlarm(QuicArenaScopedPtr<QuicAlarm::Delegate> delegate)
         : QuicAlarm(std::move(delegate)) {}

     void SetImpl() override {}
     void CancelImpl() override {}
     using QuicAlarm::Fire;
   };

   TestAlarmFactory() {}
   TestAlarmFactory(const TestAlarmFactory&) = delete;
   TestAlarmFactory& operator=(const TestAlarmFactory&) = delete;

   QuicAlarm* CreateAlarm(QuicAlarm::Delegate* delegate) override {
     return new TestAlarm(QuicArenaScopedPtr<QuicAlarm::Delegate>(delegate));
   }

   QuicArenaScopedPtr<QuicAlarm> CreateAlarm(
       QuicArenaScopedPtr<QuicAlarm::Delegate> delegate,
       QuicConnectionArena* arena) override {
     return arena->New<TestAlarm>(std::move(delegate));
   }
 };

 class TestPacketWriter : public QuicPacketWriter {
  public:
   TestPacketWriter(ParsedQuicVersion version, MockClock* clock)
       : version_(version),
         framer_(SupportedVersions(version_), Perspective::IS_SERVER),
         last_packet_size_(0),
         write_blocked_(false),
         write_should_fail_(false),
         block_on_next_flush_(false),
         block_on_next_write_(false),
         next_packet_too_large_(false),
         always_get_packet_too_large_(false),
         is_write_blocked_data_buffered_(false),
         is_batch_mode_(false),
         final_bytes_of_last_packet_(0),
         final_bytes_of_previous_packet_(0),
         use_tagging_decrypter_(false),
         packets_write_attempts_(0),
         clock_(clock),
         write_pause_time_delta_(QuicTime::Delta::Zero()),
         max_packet_size_(kMaxOutgoingPacketSize),
         supports_release_time_(false) {
     QuicFramerPeer::SetLastSerializedServerConnectionId(framer_.framer(),
                                                         TestConnectionId());
     framer_.framer()->SetInitialObfuscators(TestConnectionId());
   }
   TestPacketWriter(const TestPacketWriter&) = delete;
   TestPacketWriter& operator=(const TestPacketWriter&) = delete;

   // QuicPacketWriter interface
   WriteResult WritePacket(const char* buffer,
                           size_t buf_len,
                           const QuicIpAddress& /*self_address*/,
                           const QuicSocketAddress& /*peer_address*/,
                           PerPacketOptions* /*options*/) override {
     QuicEncryptedPacket packet(buffer, buf_len);
     ++packets_write_attempts_;

     if (packet.length() >= sizeof(final_bytes_of_last_packet_)) {
       final_bytes_of_previous_packet_ = final_bytes_of_last_packet_;
       memcpy(&final_bytes_of_last_packet_, packet.data() + packet.length() - 4,
              sizeof(final_bytes_of_last_packet_));
     }

     if (use_tagging_decrypter_) {
       if (framer_.framer()->version().KnowsWhichDecrypterToUse()) {
         framer_.framer()->InstallDecrypter(
             ENCRYPTION_INITIAL, std::make_unique<TaggingDecrypter>());
         framer_.framer()->InstallDecrypter(
             ENCRYPTION_ZERO_RTT, std::make_unique<TaggingDecrypter>());
         framer_.framer()->InstallDecrypter(
             ENCRYPTION_FORWARD_SECURE, std::make_unique<TaggingDecrypter>());
       } else {
         framer_.framer()->SetDecrypter(ENCRYPTION_INITIAL,
                                        std::make_unique<TaggingDecrypter>());
       }
     } else if (framer_.framer()->version().KnowsWhichDecrypterToUse()) {
       framer_.framer()->InstallDecrypter(
           ENCRYPTION_FORWARD_SECURE,
           std::make_unique<NullDecrypter>(Perspective::IS_SERVER));
     }
     EXPECT_TRUE(framer_.ProcessPacket(packet));
     if (block_on_next_write_) {
       write_blocked_ = true;
       block_on_next_write_ = false;
     }
     if (next_packet_too_large_) {
       next_packet_too_large_ = false;
       return WriteResult(WRITE_STATUS_ERROR, QUIC_EMSGSIZE);
     }
     if (always_get_packet_too_large_) {
       return WriteResult(WRITE_STATUS_ERROR, QUIC_EMSGSIZE);
     }
     if (IsWriteBlocked()) {
       return WriteResult(is_write_blocked_data_buffered_
                              ? WRITE_STATUS_BLOCKED_DATA_BUFFERED
                              : WRITE_STATUS_BLOCKED,
                          0);
     }

     if (ShouldWriteFail()) {
       return WriteResult(WRITE_STATUS_ERROR, 0);
     }

     last_packet_size_ = packet.length();
     last_packet_header_ = framer_.header();

     if (!write_pause_time_delta_.IsZero()) {
       clock_->AdvanceTime(write_pause_time_delta_);
     }
     return WriteResult(WRITE_STATUS_OK, last_packet_size_);
   }

   bool ShouldWriteFail() { return write_should_fail_; }

   bool IsWriteBlocked() const override { return write_blocked_; }

   void SetWriteBlocked() { write_blocked_ = true; }

   void SetWritable() override { write_blocked_ = false; }

   void SetShouldWriteFail() { write_should_fail_ = true; }

   QuicByteCount GetMaxPacketSize(
       const QuicSocketAddress& /*peer_address*/) const override {
     return max_packet_size_;
   }

   bool SupportsReleaseTime() const override { return supports_release_time_; }

   bool IsBatchMode() const override { return is_batch_mode_; }

   char* GetNextWriteLocation(
       const QuicIpAddress& /*self_address*/,
       const QuicSocketAddress& /*peer_address*/) override {
     return nullptr;
   }

   WriteResult Flush() override {
     if (block_on_next_flush_) {
       block_on_next_flush_ = false;
       SetWriteBlocked();
       return WriteResult(WRITE_STATUS_BLOCKED, /*errno*/ -1);
     }
     return WriteResult(WRITE_STATUS_OK, 0);
   }

   void BlockOnNextFlush() { block_on_next_flush_ = true; }

   void BlockOnNextWrite() { block_on_next_write_ = true; }

   void SimulateNextPacketTooLarge() { next_packet_too_large_ = true; }

   void AlwaysGetPacketTooLarge() { always_get_packet_too_large_ = true; }

   // Sets the amount of time that the writer should before the actual write.
   void SetWritePauseTimeDelta(QuicTime::Delta delta) {
     write_pause_time_delta_ = delta;
   }

   void SetBatchMode(bool new_value) { is_batch_mode_ = new_value; }

   const QuicPacketHeader& header() { return framer_.header(); }

   size_t frame_count() const { return framer_.num_frames(); }

   const std::vector<QuicAckFrame>& ack_frames() const {
     return framer_.ack_frames();
   }

   const std::vector<QuicStopWaitingFrame>& stop_waiting_frames() const {
     return framer_.stop_waiting_frames();
   }

   const std::vector<QuicConnectionCloseFrame>& connection_close_frames() const {
     return framer_.connection_close_frames();
   }

   const std::vector<QuicRstStreamFrame>& rst_stream_frames() const {
     return framer_.rst_stream_frames();
   }

   const std::vector<std::unique_ptr<QuicStreamFrame>>& stream_frames() const {
     return framer_.stream_frames();
   }

   const std::vector<std::unique_ptr<QuicCryptoFrame>>& crypto_frames() const {
     return framer_.crypto_frames();
   }

   const std::vector<QuicPingFrame>& ping_frames() const {
     return framer_.ping_frames();
   }

   const std::vector<QuicMessageFrame>& message_frames() const {
     return framer_.message_frames();
   }

   const std::vector<QuicWindowUpdateFrame>& window_update_frames() const {
     return framer_.window_update_frames();
   }

   const std::vector<QuicPaddingFrame>& padding_frames() const {
     return framer_.padding_frames();
   }

   const std::vector<QuicPathChallengeFrame>& path_challenge_frames() const {
     return framer_.path_challenge_frames();
   }

   const std::vector<QuicPathResponseFrame>& path_response_frames() const {
     return framer_.path_response_frames();
   }

   size_t last_packet_size() { return last_packet_size_; }

   const QuicPacketHeader& last_packet_header() const {
     return last_packet_header_;
   }

   const QuicVersionNegotiationPacket* version_negotiation_packet() {
     return framer_.version_negotiation_packet();
   }

   void set_is_write_blocked_data_buffered(bool buffered) {
     is_write_blocked_data_buffered_ = buffered;
   }

   void set_perspective(Perspective perspective) {
     // We invert perspective here, because the framer needs to parse packets
     // we send.
     QuicFramerPeer::SetPerspective(framer_.framer(),
                                    QuicUtils::InvertPerspective(perspective));
   }

   // final_bytes_of_last_packet_ returns the last four bytes of the previous
   // packet as a little-endian, uint32_t. This is intended to be used with a
   // TaggingEncrypter so that tests can determine which encrypter was used for
   // a given packet.
   uint32_t final_bytes_of_last_packet() { return final_bytes_of_last_packet_; }

   // Returns the final bytes of the second to last packet.
   uint32_t final_bytes_of_previous_packet() {
     return final_bytes_of_previous_packet_;
   }

   void use_tagging_decrypter() { use_tagging_decrypter_ = true; }

   uint32_t packets_write_attempts() { return packets_write_attempts_; }

   void Reset() { framer_.Reset(); }

   void SetSupportedVersions(const ParsedQuicVersionVector& versions) {
     framer_.SetSupportedVersions(versions);
   }

   void set_max_packet_size(QuicByteCount max_packet_size) {
     max_packet_size_ = max_packet_size;
   }

   void set_supports_release_time(bool supports_release_time) {
     supports_release_time_ = supports_release_time;
   }

   SimpleQuicFramer* framer() { return &framer_; }

  private:
   ParsedQuicVersion version_;
   SimpleQuicFramer framer_;
   size_t last_packet_size_;
   QuicPacketHeader last_packet_header_;
   bool write_blocked_;
   bool write_should_fail_;
   bool block_on_next_flush_;
   bool block_on_next_write_;
   bool next_packet_too_large_;
   bool always_get_packet_too_large_;
   bool is_write_blocked_data_buffered_;
   bool is_batch_mode_;
   uint32_t final_bytes_of_last_packet_;
   uint32_t final_bytes_of_previous_packet_;
   bool use_tagging_decrypter_;
   uint32_t packets_write_attempts_;
   MockClock* clock_;
   // If non-zero, the clock will pause during WritePacket for this amount of
   // time.
   QuicTime::Delta write_pause_time_delta_;
   QuicByteCount max_packet_size_;
   bool supports_release_time_;
 };

 class TestConnection : public QuicConnection {
  public:
   TestConnection(QuicConnectionId connection_id,
                  QuicSocketAddress address,
                  TestConnectionHelper* helper,
                  TestAlarmFactory* alarm_factory,
                  TestPacketWriter* writer,
                  Perspective perspective,
                  ParsedQuicVersion version)
       : QuicConnection(connection_id,
                        address,
                        helper,
                        alarm_factory,
                        writer,
                        /* owns_writer= */ false,
                        perspective,
                        SupportedVersions(version)),
         notifier_(nullptr) {
     writer->set_perspective(perspective);
     SetEncrypter(ENCRYPTION_FORWARD_SECURE,
                  std::make_unique<NullEncrypter>(perspective));
     SetDataProducer(&producer_);
   }
   TestConnection(const TestConnection&) = delete;
   TestConnection& operator=(const TestConnection&) = delete;

   void SetSendAlgorithm(SendAlgorithmInterface* send_algorithm) {
     QuicConnectionPeer::SetSendAlgorithm(this, send_algorithm);
   }

   void SetLossAlgorithm(LossDetectionInterface* loss_algorithm) {
     QuicConnectionPeer::SetLossAlgorithm(this, loss_algorithm);
   }

   void SendPacket(EncryptionLevel /*level*/,
                   uint64_t packet_number,
                   std::unique_ptr<QuicPacket> packet,
                   HasRetransmittableData retransmittable,
                   bool has_ack,
                   bool has_pending_frames) {
     char buffer[kMaxOutgoingPacketSize];
     size_t encrypted_length =
         QuicConnectionPeer::GetFramer(this)->EncryptPayload(
             ENCRYPTION_INITIAL, QuicPacketNumber(packet_number), *packet,
             buffer, kMaxOutgoingPacketSize);
     SerializedPacket serialized_packet(
         QuicPacketNumber(packet_number), PACKET_4BYTE_PACKET_NUMBER, buffer,
         encrypted_length, has_ack, has_pending_frames);
     if (retransmittable == HAS_RETRANSMITTABLE_DATA) {
       serialized_packet.retransmittable_frames.push_back(
           QuicFrame(QuicStreamFrame()));
     }
     OnSerializedPacket(&serialized_packet);
   }

   QuicConsumedData SaveAndSendStreamData(QuicStreamId id,
                                          const struct iovec* iov,
                                          int iov_count,
                                          size_t total_length,
                                          QuicStreamOffset offset,
                                          StreamSendingState state) {
     ScopedPacketFlusher flusher(this);
     producer_.SaveStreamData(id, iov, iov_count, 0u, total_length);
     if (notifier_ != nullptr) {
       return notifier_->WriteOrBufferData(id, total_length, state);
     }
     return QuicConnection::SendStreamData(id, total_length, offset, state);
   }

   QuicConsumedData SendStreamDataWithString(QuicStreamId id,
                                             QuicStringPiece data,
                                             QuicStreamOffset offset,
                                             StreamSendingState state) {
     ScopedPacketFlusher flusher(this);
     if (!QuicUtils::IsCryptoStreamId(transport_version(), id) &&
         this->encryption_level() == ENCRYPTION_INITIAL) {
       this->SetDefaultEncryptionLevel(ENCRYPTION_FORWARD_SECURE);
       if (perspective() == Perspective::IS_CLIENT && !IsHandshakeConfirmed()) {
         OnHandshakeComplete();
       }
       if (version().SupportsAntiAmplificationLimit()) {
         QuicConnectionPeer::SetAddressValidated(this);
       }
     }
     struct iovec iov;
     MakeIOVector(data, &iov);
     return SaveAndSendStreamData(id, &iov, 1, data.length(), offset, state);
   }

   QuicConsumedData SendApplicationDataAtLevel(EncryptionLevel encryption_level,
                                               QuicStreamId id,
                                               QuicStringPiece data,
                                               QuicStreamOffset offset,
                                               StreamSendingState state) {
     ScopedPacketFlusher flusher(this);
     DCHECK(encryption_level >= ENCRYPTION_ZERO_RTT);
     SetEncrypter(encryption_level, std::make_unique<TaggingEncrypter>(0x01));
     SetDefaultEncryptionLevel(encryption_level);
     struct iovec iov;
     MakeIOVector(data, &iov);
     return SaveAndSendStreamData(id, &iov, 1, data.length(), offset, state);
   }

   QuicConsumedData SendStreamData3() {
     return SendStreamDataWithString(
         GetNthClientInitiatedStreamId(1, transport_version()), "food", 0,
         NO_FIN);
   }

   QuicConsumedData SendStreamData5() {
     return SendStreamDataWithString(
         GetNthClientInitiatedStreamId(2, transport_version()), "food2", 0,
         NO_FIN);
   }

   // Ensures the connection can write stream data before writing.
   QuicConsumedData EnsureWritableAndSendStreamData5() {
     EXPECT_TRUE(CanWriteStreamData());
     return SendStreamData5();
   }

   // The crypto stream has special semantics so that it is not blocked by a
   // congestion window limitation, and also so that it gets put into a separate
   // packet (so that it is easier to reason about a crypto frame not being
   // split needlessly across packet boundaries).  As a result, we have separate
   // tests for some cases for this stream.
   QuicConsumedData SendCryptoStreamData() {
     QuicStreamOffset offset = 0;
     QuicStringPiece data("chlo");
     if (!QuicVersionUsesCryptoFrames(transport_version())) {
       return SendCryptoDataWithString(data, offset);
     }
     producer_.SaveCryptoData(ENCRYPTION_INITIAL, offset, data);
     size_t bytes_written;
     if (notifier_) {
       bytes_written =
           notifier_->WriteCryptoData(ENCRYPTION_INITIAL, data.length(), offset);
     } else {
       bytes_written = QuicConnection::SendCryptoData(ENCRYPTION_INITIAL,
                                                      data.length(), offset);
     }
     return QuicConsumedData(bytes_written, /*fin_consumed*/ false);
   }

   QuicConsumedData SendCryptoDataWithString(QuicStringPiece data,
                                             QuicStreamOffset offset) {
     if (!QuicVersionUsesCryptoFrames(transport_version())) {
       return SendStreamDataWithString(
           QuicUtils::GetCryptoStreamId(transport_version()), data, offset,
           NO_FIN);
     }
     producer_.SaveCryptoData(ENCRYPTION_INITIAL, offset, data);
     size_t bytes_written;
     if (notifier_) {
       bytes_written =
           notifier_->WriteCryptoData(ENCRYPTION_INITIAL, data.length(), offset);
     } else {
       bytes_written = QuicConnection::SendCryptoData(ENCRYPTION_INITIAL,
                                                      data.length(), offset);
     }
     return QuicConsumedData(bytes_written, /*fin_consumed*/ false);
   }

   void set_version(ParsedQuicVersion version) {
     QuicConnectionPeer::GetFramer(this)->set_version(version);
   }

   void SetSupportedVersions(const ParsedQuicVersionVector& versions) {
     QuicConnectionPeer::GetFramer(this)->SetSupportedVersions(versions);
     writer()->SetSupportedVersions(versions);
   }

   void set_perspective(Perspective perspective) {
     writer()->set_perspective(perspective);
     QuicConnectionPeer::SetPerspective(this, perspective);
   }

   // Enable path MTU discovery.  Assumes that the test is performed from the
   // client perspective and the higher value of MTU target is used.
   void EnablePathMtuDiscovery(MockSendAlgorithm* send_algorithm) {
     ASSERT_EQ(Perspective::IS_CLIENT, perspective());

     QuicConfig config;
     QuicTagVector connection_options;
     connection_options.push_back(kMTUH);
     config.SetConnectionOptionsToSend(connection_options);
     EXPECT_CALL(*send_algorithm, SetFromConfig(_, _));
     SetFromConfig(config);

     // Normally, the pacing would be disabled in the test, but calling
     // SetFromConfig enables it.  Set nearly-infinite bandwidth to make the
     // pacing algorithm work.
     EXPECT_CALL(*send_algorithm, PacingRate(_))
         .WillRepeatedly(Return(QuicBandwidth::Infinite()));
   }

   TestAlarmFactory::TestAlarm* GetAckAlarm() {
     return reinterpret_cast<TestAlarmFactory::TestAlarm*>(
         QuicConnectionPeer::GetAckAlarm(this));
   }

   TestAlarmFactory::TestAlarm* GetPingAlarm() {
     return reinterpret_cast<TestAlarmFactory::TestAlarm*>(
         QuicConnectionPeer::GetPingAlarm(this));
   }

   TestAlarmFactory::TestAlarm* GetRetransmissionAlarm() {
     return reinterpret_cast<TestAlarmFactory::TestAlarm*>(
         QuicConnectionPeer::GetRetransmissionAlarm(this));
   }

   TestAlarmFactory::TestAlarm* GetSendAlarm() {
     return reinterpret_cast<TestAlarmFactory::TestAlarm*>(
         QuicConnectionPeer::GetSendAlarm(this));
   }

   TestAlarmFactory::TestAlarm* GetTimeoutAlarm() {
     return reinterpret_cast<TestAlarmFactory::TestAlarm*>(
         QuicConnectionPeer::GetTimeoutAlarm(this));
   }

   TestAlarmFactory::TestAlarm* GetMtuDiscoveryAlarm() {
     return reinterpret_cast<TestAlarmFactory::TestAlarm*>(
         QuicConnectionPeer::GetMtuDiscoveryAlarm(this));
   }

   TestAlarmFactory::TestAlarm* GetPathDegradingAlarm() {
     return reinterpret_cast<TestAlarmFactory::TestAlarm*>(
         QuicConnectionPeer::GetPathDegradingAlarm(this));
   }

   TestAlarmFactory::TestAlarm* GetProcessUndecryptablePacketsAlarm() {
     return reinterpret_cast<TestAlarmFactory::TestAlarm*>(
         QuicConnectionPeer::GetProcessUndecryptablePacketsAlarm(this));
   }

   void SetMaxTailLossProbes(size_t max_tail_loss_probes) {
     QuicSentPacketManagerPeer::SetMaxTailLossProbes(
         QuicConnectionPeer::GetSentPacketManager(this), max_tail_loss_probes);
   }

   QuicByteCount GetBytesInFlight() {
     return QuicConnectionPeer::GetSentPacketManager(this)->GetBytesInFlight();
   }

   void set_notifier(SimpleSessionNotifier* notifier) { notifier_ = notifier; }

   void ReturnEffectivePeerAddressForNextPacket(const QuicSocketAddress& addr) {
     next_effective_peer_addr_ = std::make_unique<QuicSocketAddress>(addr);
   }

   bool PtoEnabled() {
     if (QuicConnectionPeer::GetSentPacketManager(this)->pto_enabled()) {
       // PTO mode is default enabled for T099. And TLP/RTO related tests are
       // stale.
       DCHECK_EQ(ParsedQuicVersion(PROTOCOL_TLS1_3, QUIC_VERSION_99), version());
       return true;
     }
     return false;
   }

   SimpleDataProducer* producer() { return &producer_; }

   using QuicConnection::active_effective_peer_migration_type;
   using QuicConnection::IsCurrentPacketConnectivityProbing;
   using QuicConnection::SelectMutualVersion;
   using QuicConnection::SendProbingRetransmissions;
   using QuicConnection::set_defer_send_in_response_to_packets;

  protected:
   QuicSocketAddress GetEffectivePeerAddressFromCurrentPacket() const override {
     if (next_effective_peer_addr_) {
       return *std::move(next_effective_peer_addr_);
     }
     return QuicConnection::GetEffectivePeerAddressFromCurrentPacket();
   }

  private:
   TestPacketWriter* writer() {
     return static_cast<TestPacketWriter*>(QuicConnection::writer());
   }

   SimpleDataProducer producer_;

   SimpleSessionNotifier* notifier_;

   std::unique_ptr<QuicSocketAddress> next_effective_peer_addr_;
 };

 enum class AckResponse { kDefer, kImmediate };

 // Run tests with combinations of {ParsedQuicVersion, AckResponse}.
 struct TestParams {
   TestParams(ParsedQuicVersion version,
              AckResponse ack_response,
              bool no_stop_waiting)
       : version(version),
         ack_response(ack_response),
         no_stop_waiting(no_stop_waiting) {}

   ParsedQuicVersion version;
   AckResponse ack_response;
   bool no_stop_waiting;
 };

 // Used by ::testing::PrintToStringParamName().
 std::string PrintToString(const TestParams& p) {
   return QuicStrCat(
       ParsedQuicVersionToString(p.version), "_",
       (p.ack_response == AckResponse::kDefer ? "defer" : "immediate"), "_",
       (p.no_stop_waiting ? "No" : ""), "StopWaiting");
 }

 // Constructs various test permutations.
 std::vector<TestParams> GetTestParams() {
   QuicFlagSaver flags;
   SetQuicReloadableFlag(quic_supports_tls_handshake, true);
   std::vector<TestParams> params;
   ParsedQuicVersionVector all_supported_versions = AllSupportedVersions();
   for (size_t i = 0; i < all_supported_versions.size(); ++i) {
     for (AckResponse ack_response :
          {AckResponse::kDefer, AckResponse::kImmediate}) {
       params.push_back(
           TestParams(all_supported_versions[i], ack_response, true));
       if (!VersionHasIetfInvariantHeader(
               all_supported_versions[i].transport_version)) {
         params.push_back(
             TestParams(all_supported_versions[i], ack_response, false));
       }
     }
   }
   return params;
 }

 class QuicConnectionTest : public QuicTestWithParam<TestParams> {
  public:
   // For tests that do silent connection closes, no such packet is generated. In
   // order to verify the contents of the OnConnectionClosed upcall, EXPECTs
   // should invoke this method, saving the frame, and then the test can verify
   // the contents.
   void SaveConnectionCloseFrame(const QuicConnectionCloseFrame& frame,
                                 ConnectionCloseSource /*source*/) {
     saved_connection_close_frame_ = frame;
     connection_close_frame_count_++;
   }

  protected:
   QuicConnectionTest()
       : connection_id_(TestConnectionId()),
         framer_(SupportedVersions(version()),
                 QuicTime::Zero(),
                 Perspective::IS_CLIENT,
                 connection_id_.length()),
         send_algorithm_(new StrictMock<MockSendAlgorithm>),
         loss_algorithm_(new MockLossAlgorithm()),
         helper_(new TestConnectionHelper(&clock_, &random_generator_)),
         alarm_factory_(new TestAlarmFactory()),
         peer_framer_(SupportedVersions(version()),
                      QuicTime::Zero(),
                      Perspective::IS_SERVER,
                      connection_id_.length()),
         peer_creator_(connection_id_,
                       &peer_framer_,
                       /*delegate=*/nullptr),
         writer_(new TestPacketWriter(version(), &clock_)),
         connection_(connection_id_,
                     kPeerAddress,
                     helper_.get(),
                     alarm_factory_.get(),
                     writer_.get(),
                     Perspective::IS_CLIENT,
                     version()),
         creator_(QuicConnectionPeer::GetPacketCreator(&connection_)),
         generator_(QuicConnectionPeer::GetPacketGenerator(&connection_)),
         manager_(QuicConnectionPeer::GetSentPacketManager(&connection_)),
         frame1_(0, false, 0, QuicStringPiece(data1)),
         frame2_(0, false, 3, QuicStringPiece(data2)),
         crypto_frame_(ENCRYPTION_INITIAL, 0, QuicStringPiece(data1)),
         packet_number_length_(PACKET_4BYTE_PACKET_NUMBER),
         connection_id_included_(CONNECTION_ID_PRESENT),
         notifier_(&connection_),
         connection_close_frame_count_(0) {
     QUIC_DVLOG(2) << "QuicConnectionTest(" << PrintToString(GetParam()) << ")";
     SetQuicReloadableFlag(quic_supports_tls_handshake, true);
     connection_.set_defer_send_in_response_to_packets(GetParam().ack_response ==
                                                       AckResponse::kDefer);
     framer_.SetInitialObfuscators(TestConnectionId());
     connection_.InstallInitialCrypters(TestConnectionId());
     CrypterPair crypters;
     CryptoUtils::CreateInitialObfuscators(Perspective::IS_SERVER, version(),
                                           TestConnectionId(), &crypters);
     peer_creator_.SetEncrypter(ENCRYPTION_INITIAL,
                                std::move(crypters.encrypter));
     if (version().KnowsWhichDecrypterToUse()) {
       peer_framer_.InstallDecrypter(ENCRYPTION_INITIAL,
                                     std::move(crypters.decrypter));
     } else {
       peer_framer_.SetDecrypter(ENCRYPTION_INITIAL,
                                 std::move(crypters.decrypter));
     }
     for (EncryptionLevel level :
          {ENCRYPTION_ZERO_RTT, ENCRYPTION_FORWARD_SECURE}) {
       peer_creator_.SetEncrypter(
           level, std::make_unique<NullEncrypter>(peer_framer_.perspective()));
     }
     QuicFramerPeer::SetLastSerializedServerConnectionId(
         QuicConnectionPeer::GetFramer(&connection_), connection_id_);
     QuicFramerPeer::SetLastWrittenPacketNumberLength(
         QuicConnectionPeer::GetFramer(&connection_), packet_number_length_);
     if (VersionHasIetfInvariantHeader(version().transport_version)) {
       EXPECT_TRUE(QuicConnectionPeer::GetNoStopWaitingFrames(&connection_));
     } else {
       QuicConnectionPeer::SetNoStopWaitingFrames(&connection_,
                                                  GetParam().no_stop_waiting);
     }
     QuicStreamId stream_id;
     if (QuicVersionUsesCryptoFrames(version().transport_version)) {
       stream_id = QuicUtils::GetFirstBidirectionalStreamId(
           version().transport_version, Perspective::IS_CLIENT);
     } else {
       stream_id = QuicUtils::GetCryptoStreamId(version().transport_version);
     }
     frame1_.stream_id = stream_id;
     frame2_.stream_id = stream_id;
     connection_.set_visitor(&visitor_);
     if (connection_.session_decides_what_to_write()) {
       connection_.SetSessionNotifier(&notifier_);
       connection_.set_notifier(&notifier_);
     }
     connection_.SetSendAlgorithm(send_algorithm_);
     connection_.SetLossAlgorithm(loss_algorithm_.get());
     EXPECT_CALL(*send_algorithm_, CanSend(_)).WillRepeatedly(Return(true));
     EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _))
         .Times(AnyNumber());
     EXPECT_CALL(*send_algorithm_, GetCongestionWindow())
         .WillRepeatedly(Return(kDefaultTCPMSS));
     EXPECT_CALL(*send_algorithm_, PacingRate(_))
         .WillRepeatedly(Return(QuicBandwidth::Zero()));
     EXPECT_CALL(*send_algorithm_, HasReliableBandwidthEstimate())
         .Times(AnyNumber());
     EXPECT_CALL(*send_algorithm_, BandwidthEstimate())
         .Times(AnyNumber())
         .WillRepeatedly(Return(QuicBandwidth::Zero()));
     EXPECT_CALL(*send_algorithm_, InSlowStart()).Times(AnyNumber());
     EXPECT_CALL(*send_algorithm_, InRecovery()).Times(AnyNumber());
     EXPECT_CALL(*send_algorithm_, OnApplicationLimited(_)).Times(AnyNumber());
     EXPECT_CALL(visitor_, WillingAndAbleToWrite()).Times(AnyNumber());
     EXPECT_CALL(visitor_, HasPendingHandshake()).Times(AnyNumber());
     if (connection_.session_decides_what_to_write()) {
       EXPECT_CALL(visitor_, OnCanWrite())
           .WillRepeatedly(
               Invoke(&notifier_, &SimpleSessionNotifier::OnCanWrite));
     } else {
       EXPECT_CALL(visitor_, OnCanWrite()).Times(AnyNumber());
     }
     EXPECT_CALL(visitor_, ShouldKeepConnectionAlive())
         .WillRepeatedly(Return(false));
     EXPECT_CALL(visitor_, OnCongestionWindowChange(_)).Times(AnyNumber());
     EXPECT_CALL(visitor_, OnPacketReceived(_, _, _)).Times(AnyNumber());
     EXPECT_CALL(visitor_, OnForwardProgressConfirmed()).Times(AnyNumber());

     EXPECT_CALL(*loss_algorithm_, GetLossTimeout())
         .WillRepeatedly(Return(QuicTime::Zero()));
     EXPECT_CALL(*loss_algorithm_, DetectLosses(_, _, _, _, _, _))
         .Times(AnyNumber());

     if (connection_.version().KnowsWhichDecrypterToUse()) {
       connection_.InstallDecrypter(
           ENCRYPTION_FORWARD_SECURE,
           std::make_unique<NullDecrypter>(Perspective::IS_CLIENT));
     }
   }

   QuicConnectionTest(const QuicConnectionTest&) = delete;
   QuicConnectionTest& operator=(const QuicConnectionTest&) = delete;

   ParsedQuicVersion version() { return GetParam().version; }

   QuicStopWaitingFrame* stop_waiting() {
     QuicConnectionPeer::PopulateStopWaitingFrame(&connection_, &stop_waiting_);
     return &stop_waiting_;
   }

   QuicPacketNumber least_unacked() {
     if (writer_->stop_waiting_frames().empty()) {
       return QuicPacketNumber();
     }
     return writer_->stop_waiting_frames()[0].least_unacked;
   }

   void use_tagging_decrypter() { writer_->use_tagging_decrypter(); }

   void SetDecrypter(EncryptionLevel level,
                     std::unique_ptr<QuicDecrypter> decrypter) {
     if (connection_.version().KnowsWhichDecrypterToUse()) {
       connection_.InstallDecrypter(level, std::move(decrypter));
       connection_.RemoveDecrypter(ENCRYPTION_INITIAL);
     } else {
       connection_.SetDecrypter(level, std::move(decrypter));
     }
   }

   void ProcessPacket(uint64_t number) {
     EXPECT_CALL(visitor_, OnStreamFrame(_)).Times(1);
     ProcessDataPacket(number);
     if (connection_.GetSendAlarm()->IsSet()) {
       connection_.GetSendAlarm()->Fire();
     }
   }

   void ProcessReceivedPacket(const QuicSocketAddress& self_address,
                              const QuicSocketAddress& peer_address,
                              const QuicReceivedPacket& packet) {
     connection_.ProcessUdpPacket(self_address, peer_address, packet);
     if (connection_.GetSendAlarm()->IsSet()) {
       connection_.GetSendAlarm()->Fire();
     }
   }

   void ProcessFramePacket(QuicFrame frame) {
     ProcessFramePacketWithAddresses(frame, kSelfAddress, kPeerAddress);
   }

   void ProcessFramePacketWithAddresses(QuicFrame frame,
                                        QuicSocketAddress self_address,
                                        QuicSocketAddress peer_address) {
     QuicFrames frames;
     frames.push_back(QuicFrame(frame));
     QuicPacketCreatorPeer::SetSendVersionInPacket(
         &peer_creator_, connection_.perspective() == Perspective::IS_SERVER);

     char buffer[kMaxOutgoingPacketSize];
     SerializedPacket serialized_packet =
         QuicPacketCreatorPeer::SerializeAllFrames(
             &peer_creator_, frames, buffer, kMaxOutgoingPacketSize);
     connection_.ProcessUdpPacket(
         self_address, peer_address,
         QuicReceivedPacket(serialized_packet.encrypted_buffer,
                            serialized_packet.encrypted_length, clock_.Now()));
     if (connection_.GetSendAlarm()->IsSet()) {
       connection_.GetSendAlarm()->Fire();
     }
   }

   // Bypassing the packet creator is unrealistic, but allows us to process
   // packets the QuicPacketCreator won't allow us to create.
   void ForceProcessFramePacket(QuicFrame frame) {
     QuicFrames frames;
     frames.push_back(QuicFrame(frame));
     bool send_version = connection_.perspective() == Perspective::IS_SERVER;
     if (connection_.version().KnowsWhichDecrypterToUse()) {
       send_version = true;
     }
     QuicPacketCreatorPeer::SetSendVersionInPacket(&peer_creator_, send_version);
     QuicPacketHeader header;
     QuicPacketCreatorPeer::FillPacketHeader(&peer_creator_, &header);
     char encrypted_buffer[kMaxOutgoingPacketSize];
     size_t length = peer_framer_.BuildDataPacket(
         header, frames, encrypted_buffer, kMaxOutgoingPacketSize,
         ENCRYPTION_INITIAL);
     DCHECK_GT(length, 0u);

     const size_t encrypted_length = peer_framer_.EncryptInPlace(
         ENCRYPTION_INITIAL, header.packet_number,
         GetStartOfEncryptedData(peer_framer_.version().transport_version,
                                 header),
         length, kMaxOutgoingPacketSize, encrypted_buffer);
     DCHECK_GT(encrypted_length, 0u);

     connection_.ProcessUdpPacket(
         kSelfAddress, kPeerAddress,
         QuicReceivedPacket(encrypted_buffer, encrypted_length, clock_.Now()));
   }

   size_t ProcessFramePacketAtLevel(uint64_t number,
                                    QuicFrame frame,
                                    EncryptionLevel level) {
     QuicPacketHeader header;
     header.destination_connection_id = connection_id_;
     header.packet_number_length = packet_number_length_;
     header.destination_connection_id_included = connection_id_included_;
     if (peer_framer_.perspective() == Perspective::IS_SERVER) {
       header.destination_connection_id_included = CONNECTION_ID_ABSENT;
     }
     if (level == ENCRYPTION_INITIAL &&
         peer_framer_.version().KnowsWhichDecrypterToUse()) {
       header.version_flag = true;
       if (QuicVersionHasLongHeaderLengths(peer_framer_.transport_version())) {
         header.retry_token_length_length = VARIABLE_LENGTH_INTEGER_LENGTH_1;
         header.length_length = VARIABLE_LENGTH_INTEGER_LENGTH_2;
       }
     }
     if (header.version_flag &&
         peer_framer_.perspective() == Perspective::IS_SERVER) {
       header.source_connection_id = connection_id_;
       header.source_connection_id_included = CONNECTION_ID_PRESENT;
     }
     header.packet_number = QuicPacketNumber(number);
     QuicFrames frames;
     frames.push_back(frame);
     std::unique_ptr<QuicPacket> packet(ConstructPacket(header, frames));
     // Set the correct encryption level and encrypter on peer_creator and
     // peer_framer, respectively.
     peer_creator_.set_encryption_level(level);
     if (QuicPacketCreatorPeer::GetEncryptionLevel(&peer_creator_) >
         ENCRYPTION_INITIAL) {
       peer_framer_.SetEncrypter(
           QuicPacketCreatorPeer::GetEncryptionLevel(&peer_creator_),
           std::make_unique<TaggingEncrypter>(0x01));
       // Set the corresponding decrypter.
       if (connection_.version().KnowsWhichDecrypterToUse()) {
         connection_.InstallDecrypter(
             QuicPacketCreatorPeer::GetEncryptionLevel(&peer_creator_),
             std::make_unique<StrictTaggingDecrypter>(0x01));
         connection_.RemoveDecrypter(ENCRYPTION_INITIAL);
       } else {
         connection_.SetDecrypter(
             QuicPacketCreatorPeer::GetEncryptionLevel(&peer_creator_),
             std::make_unique<StrictTaggingDecrypter>(0x01));
       }
     }

     char buffer[kMaxOutgoingPacketSize];
     size_t encrypted_length =
         peer_framer_.EncryptPayload(level, QuicPacketNumber(number), *packet,
                                     buffer, kMaxOutgoingPacketSize);
     connection_.ProcessUdpPacket(
         kSelfAddress, kPeerAddress,
         QuicReceivedPacket(buffer, encrypted_length, clock_.Now(), false));
     if (connection_.GetSendAlarm()->IsSet()) {
       connection_.GetSendAlarm()->Fire();
     }
     return encrypted_length;
   }

   size_t ProcessDataPacket(uint64_t number) {
     return ProcessDataPacketAtLevel(number, false, ENCRYPTION_FORWARD_SECURE);
   }

   size_t ProcessDataPacket(QuicPacketNumber packet_number) {
     return ProcessDataPacketAtLevel(packet_number, false,
                                     ENCRYPTION_FORWARD_SECURE);
   }

   size_t ProcessDataPacketAtLevel(QuicPacketNumber packet_number,
                                   bool has_stop_waiting,
                                   EncryptionLevel level) {
     return ProcessDataPacketAtLevel(packet_number.ToUint64(), has_stop_waiting,
                                     level);
   }

   size_t ProcessCryptoPacketAtLevel(uint64_t number,
                                     EncryptionLevel /*level*/) {
     QuicPacketHeader header = ConstructPacketHeader(number, ENCRYPTION_INITIAL);
     QuicFrames frames;
     if (QuicVersionUsesCryptoFrames(connection_.transport_version())) {
       frames.push_back(QuicFrame(&crypto_frame_));
     } else {
       frames.push_back(QuicFrame(frame1_));
     }
     frames.push_back(QuicFrame(QuicPaddingFrame(-1)));
     std::unique_ptr<QuicPacket> packet = ConstructPacket(header, frames);
     char buffer[kMaxOutgoingPacketSize];
     peer_creator_.set_encryption_level(ENCRYPTION_INITIAL);
     size_t encrypted_length = peer_framer_.EncryptPayload(
         ENCRYPTION_INITIAL, QuicPacketNumber(number), *packet, buffer,
         kMaxOutgoingPacketSize);
     connection_.ProcessUdpPacket(
         kSelfAddress, kPeerAddress,
         QuicReceivedPacket(buffer, encrypted_length, clock_.Now(), false));
     if (connection_.GetSendAlarm()->IsSet()) {
       connection_.GetSendAlarm()->Fire();
     }
     return encrypted_length;
   }

   size_t ProcessDataPacketAtLevel(uint64_t number,
                                   bool has_stop_waiting,
                                   EncryptionLevel level) {
     std::unique_ptr<QuicPacket> packet(
         ConstructDataPacket(number, has_stop_waiting, level));
     char buffer[kMaxOutgoingPacketSize];
     peer_creator_.set_encryption_level(level);
     size_t encrypted_length =
         peer_framer_.EncryptPayload(level, QuicPacketNumber(number), *packet,
                                     buffer, kMaxOutgoingPacketSize);
     connection_.ProcessUdpPacket(
         kSelfAddress, kPeerAddress,
         QuicReceivedPacket(buffer, encrypted_length, clock_.Now(), false));
     if (connection_.GetSendAlarm()->IsSet()) {
       connection_.GetSendAlarm()->Fire();
     }
     return encrypted_length;
   }

   void ProcessClosePacket(uint64_t number) {
     std::unique_ptr<QuicPacket> packet(ConstructClosePacket(number));
     char buffer[kMaxOutgoingPacketSize];
     size_t encrypted_length = peer_framer_.EncryptPayload(
         ENCRYPTION_FORWARD_SECURE, QuicPacketNumber(number), *packet, buffer,
         kMaxOutgoingPacketSize);
     connection_.ProcessUdpPacket(
         kSelfAddress, kPeerAddress,
         QuicReceivedPacket(buffer, encrypted_length, QuicTime::Zero(), false));
   }

   QuicByteCount SendStreamDataToPeer(QuicStreamId id,
                                      QuicStringPiece data,
                                      QuicStreamOffset offset,
                                      StreamSendingState state,
                                      QuicPacketNumber* last_packet) {
     QuicByteCount packet_size;
     // Save the last packet's size.
     EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _))
         .Times(AnyNumber())
         .WillRepeatedly(SaveArg<3>(&packet_size));
     connection_.SendStreamDataWithString(id, data, offset, state);
     if (last_packet != nullptr) {
       *last_packet = creator_->packet_number();
     }
     EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _))
         .Times(AnyNumber());
     return packet_size;
   }

   void SendAckPacketToPeer() {
     EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(1);
     {
       QuicConnection::ScopedPacketFlusher flusher(&connection_);
       connection_.SendAck();
     }
     EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _))
         .Times(AnyNumber());
   }

   void SendRstStream(QuicStreamId id,
                      QuicRstStreamErrorCode error,
                      QuicStreamOffset bytes_written) {
     if (connection_.session_decides_what_to_write()) {
       notifier_.WriteOrBufferRstStream(id, error, bytes_written);
       connection_.OnStreamReset(id, error);
       return;
     }
     std::unique_ptr<QuicRstStreamFrame> rst_stream =
         std::make_unique<QuicRstStreamFrame>(1, id, error, bytes_written);
     if (connection_.SendControlFrame(QuicFrame(rst_stream.get()))) {
       rst_stream.release();
     }
     connection_.OnStreamReset(id, error);
   }

   void SendPing() {
     if (connection_.session_decides_what_to_write()) {
       notifier_.WriteOrBufferPing();
     } else {
       connection_.SendControlFrame(QuicFrame(QuicPingFrame(1)));
     }
   }

   void ProcessAckPacket(uint64_t packet_number, QuicAckFrame* frame) {
     if (packet_number > 1) {
       QuicPacketCreatorPeer::SetPacketNumber(&peer_creator_, packet_number - 1);
     } else {
       QuicPacketCreatorPeer::ClearPacketNumber(&peer_creator_);
     }
     ProcessFramePacket(QuicFrame(frame));
   }

   void ProcessAckPacket(QuicAckFrame* frame) {
     ProcessFramePacket(QuicFrame(frame));
   }

   void ProcessStopWaitingPacket(QuicStopWaitingFrame frame) {
     ProcessFramePacket(QuicFrame(frame));
   }

   size_t ProcessStopWaitingPacketAtLevel(uint64_t number,
                                          QuicStopWaitingFrame frame,
                                          EncryptionLevel /*level*/) {
     return ProcessFramePacketAtLevel(number, QuicFrame(frame),
                                      ENCRYPTION_ZERO_RTT);
   }

   void ProcessGoAwayPacket(QuicGoAwayFrame* frame) {
     ProcessFramePacket(QuicFrame(frame));
   }

   bool IsMissing(uint64_t number) {
     return IsAwaitingPacket(connection_.ack_frame(), QuicPacketNumber(number),
                             QuicPacketNumber());
   }

   std::unique_ptr<QuicPacket> ConstructPacket(const QuicPacketHeader& header,
                                               const QuicFrames& frames) {
     auto packet = BuildUnsizedDataPacket(&peer_framer_, header, frames);
     EXPECT_NE(nullptr, packet.get());
     return packet;
   }

   QuicPacketHeader ConstructPacketHeader(uint64_t number,
                                          EncryptionLevel level) {
     QuicPacketHeader header;
     if (VersionHasIetfInvariantHeader(peer_framer_.transport_version()) &&
         level < ENCRYPTION_FORWARD_SECURE) {
       // Set long header type accordingly.
       header.version_flag = true;
       header.form = IETF_QUIC_LONG_HEADER_PACKET;
       header.long_packet_type = EncryptionlevelToLongHeaderType(level);
       if (QuicVersionHasLongHeaderLengths(
               peer_framer_.version().transport_version)) {
         header.length_length = VARIABLE_LENGTH_INTEGER_LENGTH_2;
         if (header.long_packet_type == INITIAL) {
           header.retry_token_length_length = VARIABLE_LENGTH_INTEGER_LENGTH_1;
         }
       }
     }
     // Set connection_id to peer's in memory representation as this data packet
     // is created by peer_framer.
     if (peer_framer_.perspective() == Perspective::IS_SERVER) {
       header.source_connection_id = connection_id_;
       header.source_connection_id_included = connection_id_included_;
       header.destination_connection_id_included = CONNECTION_ID_ABSENT;
     } else {
       header.destination_connection_id = connection_id_;
       header.destination_connection_id_included = connection_id_included_;
     }
     if (VersionHasIetfInvariantHeader(peer_framer_.transport_version()) &&
         peer_framer_.perspective() == Perspective::IS_SERVER) {
       header.destination_connection_id_included = CONNECTION_ID_ABSENT;
       if (header.version_flag) {
         header.source_connection_id = connection_id_;
         header.source_connection_id_included = CONNECTION_ID_PRESENT;
         if (GetParam().version.handshake_protocol == PROTOCOL_QUIC_CRYPTO &&
             header.long_packet_type == ZERO_RTT_PROTECTED) {
           header.nonce = &kTestDiversificationNonce;
         }
       }
     }
     header.packet_number_length = packet_number_length_;
     header.packet_number = QuicPacketNumber(number);
     return header;
   }

   std::unique_ptr<QuicPacket> ConstructDataPacket(uint64_t number,
                                                   bool has_stop_waiting,
                                                   EncryptionLevel level) {
     QuicPacketHeader header = ConstructPacketHeader(number, level);
     QuicFrames frames;
     frames.push_back(QuicFrame(frame1_));
     if (has_stop_waiting) {
       frames.push_back(QuicFrame(stop_waiting_));
     }
     return ConstructPacket(header, frames);
   }

   OwningSerializedPacketPointer ConstructProbingPacket() {
     if (VersionHasIetfQuicFrames(version().transport_version)) {
       QuicPathFrameBuffer payload = {
           {0xde, 0xad, 0xbe, 0xef, 0xba, 0xdc, 0x0f, 0xfe}};
       return QuicPacketCreatorPeer::
           SerializePathChallengeConnectivityProbingPacket(&peer_creator_,
                                                           &payload);
     }
     return QuicPacketCreatorPeer::SerializeConnectivityProbingPacket(
         &peer_creator_);
   }

   std::unique_ptr<QuicPacket> ConstructClosePacket(uint64_t number) {
     QuicPacketHeader header;
     // Set connection_id to peer's in memory representation as this connection
     // close packet is created by peer_framer.
     if (peer_framer_.perspective() == Perspective::IS_SERVER) {
       header.source_connection_id = connection_id_;
       header.destination_connection_id_included = CONNECTION_ID_ABSENT;
       if (!VersionHasIetfInvariantHeader(peer_framer_.transport_version())) {
         header.source_connection_id_included = CONNECTION_ID_PRESENT;
       }
     } else {
       header.destination_connection_id = connection_id_;
       if (VersionHasIetfInvariantHeader(peer_framer_.transport_version())) {
         header.destination_connection_id_included = CONNECTION_ID_ABSENT;
       }
     }

     header.packet_number = QuicPacketNumber(number);

     QuicErrorCode kQuicErrorCode = QUIC_PEER_GOING_AWAY;
     QuicConnectionCloseFrame qccf(peer_framer_.transport_version(),
                                   kQuicErrorCode, "",
                                   /*transport_close_frame_type=*/0);
     QuicFrames frames;
     frames.push_back(QuicFrame(&qccf));
     return ConstructPacket(header, frames);
   }

   QuicTime::Delta DefaultRetransmissionTime() {
     return QuicTime::Delta::FromMilliseconds(kDefaultRetransmissionTimeMs);
   }

   QuicTime::Delta DefaultDelayedAckTime() {
     return QuicTime::Delta::FromMilliseconds(kDefaultDelayedAckTimeMs);
   }

   const QuicStopWaitingFrame InitStopWaitingFrame(uint64_t least_unacked) {
     QuicStopWaitingFrame frame;
     frame.least_unacked = QuicPacketNumber(least_unacked);
     return frame;
   }

   // Construct a ack_frame that acks all packet numbers between 1 and
   // |largest_acked|, except |missing|.
   // REQUIRES: 1 <= |missing| < |largest_acked|
   QuicAckFrame ConstructAckFrame(uint64_t largest_acked, uint64_t missing) {
     return ConstructAckFrame(QuicPacketNumber(largest_acked),
                              QuicPacketNumber(missing));
   }

   QuicAckFrame ConstructAckFrame(QuicPacketNumber largest_acked,
                                  QuicPacketNumber missing) {
     if (missing == QuicPacketNumber(1)) {
       return InitAckFrame({{missing + 1, largest_acked + 1}});
     }
     return InitAckFrame(
         {{QuicPacketNumber(1), missing}, {missing + 1, largest_acked + 1}});
   }

   // Undo nacking a packet within the frame.
   void AckPacket(QuicPacketNumber arrived, QuicAckFrame* frame) {
     EXPECT_FALSE(frame->packets.Contains(arrived));
     frame->packets.Add(arrived);
   }

   void TriggerConnectionClose() {
     // Send an erroneous packet to close the connection.
     EXPECT_CALL(visitor_,
                 OnConnectionClosed(_, ConnectionCloseSource::FROM_SELF))
         .WillOnce(Invoke(this, &QuicConnectionTest::SaveConnectionCloseFrame));

     EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
     // Triggers a connection by receiving ACK of unsent packet.
     QuicAckFrame frame = InitAckFrame(10000);
     ProcessAckPacket(1, &frame);
     EXPECT_FALSE(QuicConnectionPeer::GetConnectionClosePacket(&connection_) ==
                  nullptr);
     EXPECT_EQ(1, connection_close_frame_count_);
     EXPECT_EQ(QUIC_INVALID_ACK_DATA,
               saved_connection_close_frame_.quic_error_code);
   }

   void BlockOnNextWrite() {
     writer_->BlockOnNextWrite();
     EXPECT_CALL(visitor_, OnWriteBlocked()).Times(AtLeast(1));
   }

   void SimulateNextPacketTooLarge() { writer_->SimulateNextPacketTooLarge(); }

   void AlwaysGetPacketTooLarge() { writer_->AlwaysGetPacketTooLarge(); }

   void SetWritePauseTimeDelta(QuicTime::Delta delta) {
     writer_->SetWritePauseTimeDelta(delta);
   }

   void CongestionBlockWrites() {
     EXPECT_CALL(*send_algorithm_, CanSend(_))
         .WillRepeatedly(testing::Return(false));
   }

   void CongestionUnblockWrites() {
     EXPECT_CALL(*send_algorithm_, CanSend(_))
         .WillRepeatedly(testing::Return(true));
   }

   void set_perspective(Perspective perspective) {
     connection_.set_perspective(perspective);
     if (perspective == Perspective::IS_SERVER) {
       connection_.set_can_truncate_connection_ids(true);
     }
     QuicFramerPeer::SetPerspective(&peer_framer_,
                                    QuicUtils::InvertPerspective(perspective));
   }

   void set_packets_between_probes_base(
       const QuicPacketCount packets_between_probes_base) {
     if (GetQuicReloadableFlag(quic_mtu_discovery_v2)) {
       QuicConnectionPeer::ReInitializeMtuDiscoverer(
           &connection_, packets_between_probes_base,
           QuicPacketNumber(packets_between_probes_base));
     } else {
       QuicConnectionPeer::SetPacketsBetweenMtuProbes(
           &connection_, packets_between_probes_base);
       QuicConnectionPeer::SetNextMtuProbeAt(
           &connection_, QuicPacketNumber(packets_between_probes_base));
     }
   }

   bool IsDefaultTestConfiguration() {
     TestParams p = GetParam();
     return p.ack_response == AckResponse::kImmediate &&
            p.version == AllSupportedVersions()[0] && p.no_stop_waiting;
   }

   void TestConnectionCloseQuicErrorCode(QuicErrorCode expected_code) {
     // Not strictly needed for this test, but is commonly done.
     EXPECT_FALSE(QuicConnectionPeer::GetConnectionClosePacket(&connection_) ==
                  nullptr);
     const std::vector<QuicConnectionCloseFrame>& connection_close_frames =
         writer_->connection_close_frames();
     ASSERT_EQ(1u, connection_close_frames.size());
     if (!VersionHasIetfQuicFrames(version().transport_version)) {
       EXPECT_EQ(expected_code, connection_close_frames[0].quic_error_code);
       EXPECT_EQ(GOOGLE_QUIC_CONNECTION_CLOSE,
                 connection_close_frames[0].close_type);
       return;
     }

     QuicErrorCodeToIetfMapping mapping =
         QuicErrorCodeToTransportErrorCode(expected_code);

     if (mapping.is_transport_close_) {
       // This Google QUIC Error Code maps to a transport close,
       EXPECT_EQ(IETF_QUIC_TRANSPORT_CONNECTION_CLOSE,
                 connection_close_frames[0].close_type);
       EXPECT_EQ(mapping.transport_error_code_,
                 connection_close_frames[0].transport_error_code);
       // TODO(fkastenholz): when the extracted error code CL lands,
       // need to test that extracted==expected.
     } else {
       // This maps to an application close.
       EXPECT_EQ(expected_code, connection_close_frames[0].quic_error_code);
       EXPECT_EQ(IETF_QUIC_APPLICATION_CONNECTION_CLOSE,
                 connection_close_frames[0].close_type);
       // TODO(fkastenholz): when the extracted error code CL lands,
       // need to test that extracted==expected.
     }
   }

   QuicConnectionId connection_id_;
   QuicFramer framer_;

   MockSendAlgorithm* send_algorithm_;
   std::unique_ptr<MockLossAlgorithm> loss_algorithm_;
   MockClock clock_;
   MockRandom random_generator_;
   SimpleBufferAllocator buffer_allocator_;
   std::unique_ptr<TestConnectionHelper> helper_;
   std::unique_ptr<TestAlarmFactory> alarm_factory_;
   QuicFramer peer_framer_;
   QuicPacketCreator peer_creator_;
   std::unique_ptr<TestPacketWriter> writer_;
   TestConnection connection_;
   QuicPacketCreator* creator_;
   QuicPacketGenerator* generator_;
   QuicSentPacketManager* manager_;
   StrictMock<MockQuicConnectionVisitor> visitor_;

   QuicStreamFrame frame1_;
   QuicStreamFrame frame2_;
   QuicCryptoFrame crypto_frame_;
   QuicAckFrame ack_;
   QuicStopWaitingFrame stop_waiting_;
   QuicPacketNumberLength packet_number_length_;
   QuicConnectionIdIncluded connection_id_included_;

   SimpleSessionNotifier notifier_;

   QuicConnectionCloseFrame saved_connection_close_frame_;
   int connection_close_frame_count_;
 };

 // Run all end to end tests with all supported versions.
 INSTANTIATE_TEST_SUITE_P(SupportedVersion,
                          QuicConnectionTest,
                          ::testing::ValuesIn(GetTestParams()),
                          ::testing::PrintToStringParamName());

 // These two tests ensure that the QuicErrorCode mapping works correctly.
 // Both tests expect to see a Google QUIC close if not running IETF QUIC.
 // If running IETF QUIC, the first will generate a transport connection
 // close, the second an application connection close.
 // The connection close codes for the two tests are manually chosen;
 // they are expected to always map to transport- and application-
 // closes, respectively. If that changes, mew codes should be chosen.
 TEST_P(QuicConnectionTest, CloseErrorCodeTestTransport) {
   EXPECT_TRUE(connection_.connected());
   EXPECT_CALL(visitor_, OnConnectionClosed(_, _));
   connection_.CloseConnection(
       IETF_QUIC_PROTOCOL_VIOLATION, "Should be transport close",
       ConnectionCloseBehavior::SEND_CONNECTION_CLOSE_PACKET);
   EXPECT_FALSE(connection_.connected());
   TestConnectionCloseQuicErrorCode(IETF_QUIC_PROTOCOL_VIOLATION);
 }

 // Test that the IETF QUIC Error code mapping function works
 // properly for application connection close codes.
 TEST_P(QuicConnectionTest, CloseErrorCodeTestApplication) {
   EXPECT_TRUE(connection_.connected());
   EXPECT_CALL(visitor_, OnConnectionClosed(_, _));
   connection_.CloseConnection(
       QUIC_HEADERS_STREAM_DATA_DECOMPRESS_FAILURE,
       "Should be application close",
       ConnectionCloseBehavior::SEND_CONNECTION_CLOSE_PACKET);
   EXPECT_FALSE(connection_.connected());
   TestConnectionCloseQuicErrorCode(QUIC_HEADERS_STREAM_DATA_DECOMPRESS_FAILURE);
 }

 TEST_P(QuicConnectionTest, SelfAddressChangeAtClient) {
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));

   EXPECT_EQ(Perspective::IS_CLIENT, connection_.perspective());
   EXPECT_TRUE(connection_.connected());

   QuicFrame frame;
   if (QuicVersionUsesCryptoFrames(connection_.transport_version())) {
     frame = QuicFrame(&crypto_frame_);
     EXPECT_CALL(visitor_, OnCryptoFrame(_));
   } else {
     frame = QuicFrame(QuicStreamFrame(
         QuicUtils::GetCryptoStreamId(connection_.transport_version()), false,
         0u, QuicStringPiece()));
     EXPECT_CALL(visitor_, OnStreamFrame(_));
   }
   ProcessFramePacketWithAddresses(frame, kSelfAddress, kPeerAddress);
   // Cause change in self_address.
   QuicIpAddress host;
   host.FromString("1.1.1.1");
   QuicSocketAddress self_address(host, 123);
   if (QuicVersionUsesCryptoFrames(connection_.transport_version())) {
     EXPECT_CALL(visitor_, OnCryptoFrame(_));
   } else {
     EXPECT_CALL(visitor_, OnStreamFrame(_));
   }
   ProcessFramePacketWithAddresses(frame, self_address, kPeerAddress);
   EXPECT_TRUE(connection_.connected());
 }

 TEST_P(QuicConnectionTest, SelfAddressChangeAtServer) {
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));

   set_perspective(Perspective::IS_SERVER);
   QuicPacketCreatorPeer::SetSendVersionInPacket(creator_, false);

   EXPECT_EQ(Perspective::IS_SERVER, connection_.perspective());
   EXPECT_TRUE(connection_.connected());

   QuicFrame frame;
   if (QuicVersionUsesCryptoFrames(connection_.transport_version())) {
     frame = QuicFrame(&crypto_frame_);
     EXPECT_CALL(visitor_, OnCryptoFrame(_));
   } else {
     frame = QuicFrame(QuicStreamFrame(
         QuicUtils::GetCryptoStreamId(connection_.transport_version()), false,
         0u, QuicStringPiece()));
     EXPECT_CALL(visitor_, OnStreamFrame(_));
   }
   ProcessFramePacketWithAddresses(frame, kSelfAddress, kPeerAddress);
   // Cause change in self_address.
   QuicIpAddress host;
   host.FromString("1.1.1.1");
   QuicSocketAddress self_address(host, 123);
   EXPECT_CALL(visitor_, AllowSelfAddressChange()).WillOnce(Return(false));
   EXPECT_CALL(visitor_, OnConnectionClosed(_, _));
   ProcessFramePacketWithAddresses(frame, self_address, kPeerAddress);
   EXPECT_FALSE(connection_.connected());
   TestConnectionCloseQuicErrorCode(QUIC_ERROR_MIGRATING_ADDRESS);
 }

 TEST_P(QuicConnectionTest, AllowSelfAddressChangeToMappedIpv4AddressAtServer) {
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));

   set_perspective(Perspective::IS_SERVER);
   QuicPacketCreatorPeer::SetSendVersionInPacket(creator_, false);

   EXPECT_EQ(Perspective::IS_SERVER, connection_.perspective());
   EXPECT_TRUE(connection_.connected());

   QuicFrame frame;
   if (QuicVersionUsesCryptoFrames(connection_.transport_version())) {
     frame = QuicFrame(&crypto_frame_);
     EXPECT_CALL(visitor_, OnCryptoFrame(_)).Times(3);
   } else {
     frame = QuicFrame(QuicStreamFrame(
         QuicUtils::GetCryptoStreamId(connection_.transport_version()), false,
         0u, QuicStringPiece()));
     EXPECT_CALL(visitor_, OnStreamFrame(_)).Times(3);
   }
   QuicIpAddress host;
   host.FromString("1.1.1.1");
   QuicSocketAddress self_address1(host, 443);
   ProcessFramePacketWithAddresses(frame, self_address1, kPeerAddress);
   // Cause self_address change to mapped Ipv4 address.
   QuicIpAddress host2;
   host2.FromString(
       QuicStrCat("::ffff:", connection_.self_address().host().ToString()));
   QuicSocketAddress self_address2(host2, connection_.self_address().port());
   ProcessFramePacketWithAddresses(frame, self_address2, kPeerAddress);
   EXPECT_TRUE(connection_.connected());
   // self_address change back to Ipv4 address.
   ProcessFramePacketWithAddresses(frame, self_address1, kPeerAddress);
   EXPECT_TRUE(connection_.connected());
 }

 TEST_P(QuicConnectionTest, ClientAddressChangeAndPacketReordered) {
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
   set_perspective(Perspective::IS_SERVER);
   QuicPacketCreatorPeer::SetSendVersionInPacket(creator_, false);

   // Clear direct_peer_address.
   QuicConnectionPeer::SetDirectPeerAddress(&connection_, QuicSocketAddress());
   // Clear effective_peer_address, it is the same as direct_peer_address for
   // this test.
   QuicConnectionPeer::SetEffectivePeerAddress(&connection_,
                                               QuicSocketAddress());

   QuicFrame frame;
   if (QuicVersionUsesCryptoFrames(connection_.transport_version())) {
     frame = QuicFrame(&crypto_frame_);
     EXPECT_CALL(visitor_, OnCryptoFrame(_)).Times(AnyNumber());
   } else {
     frame = QuicFrame(QuicStreamFrame(
         QuicUtils::GetCryptoStreamId(connection_.transport_version()), false,
         0u, QuicStringPiece()));
     EXPECT_CALL(visitor_, OnStreamFrame(_)).Times(AnyNumber());
   }
   QuicPacketCreatorPeer::SetPacketNumber(&peer_creator_, 5);
   const QuicSocketAddress kNewPeerAddress =
       QuicSocketAddress(QuicIpAddress::Loopback6(),
                         /*port=*/23456);
   ProcessFramePacketWithAddresses(frame, kSelfAddress, kNewPeerAddress);
   EXPECT_EQ(kNewPeerAddress, connection_.peer_address());
   EXPECT_EQ(kNewPeerAddress, connection_.effective_peer_address());

   // Decrease packet number to simulate out-of-order packets.
   QuicPacketCreatorPeer::SetPacketNumber(&peer_creator_, 4);
   // This is an old packet, do not migrate.
   EXPECT_CALL(visitor_, OnConnectionMigration(PORT_CHANGE)).Times(0);
   ProcessFramePacketWithAddresses(frame, kSelfAddress, kPeerAddress);
   EXPECT_EQ(kNewPeerAddress, connection_.peer_address());
   EXPECT_EQ(kNewPeerAddress, connection_.effective_peer_address());
 }

 TEST_P(QuicConnectionTest, PeerAddressChangeAtServer) {
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
   set_perspective(Perspective::IS_SERVER);
   QuicPacketCreatorPeer::SetSendVersionInPacket(creator_, false);
   EXPECT_EQ(Perspective::IS_SERVER, connection_.perspective());

   // Clear direct_peer_address.
   QuicConnectionPeer::SetDirectPeerAddress(&connection_, QuicSocketAddress());
   // Clear effective_peer_address, it is the same as direct_peer_address for
   // this test.
   QuicConnectionPeer::SetEffectivePeerAddress(&connection_,
                                               QuicSocketAddress());
   EXPECT_FALSE(connection_.effective_peer_address().IsInitialized());

   QuicFrame frame;
   if (QuicVersionUsesCryptoFrames(connection_.transport_version())) {
     frame = QuicFrame(&crypto_frame_);
     EXPECT_CALL(visitor_, OnCryptoFrame(_)).Times(AnyNumber());
   } else {
     frame = QuicFrame(QuicStreamFrame(
         QuicUtils::GetCryptoStreamId(connection_.transport_version()), false,
         0u, QuicStringPiece()));
     EXPECT_CALL(visitor_, OnStreamFrame(_)).Times(AnyNumber());
   }
   ProcessFramePacketWithAddresses(frame, kSelfAddress, kPeerAddress);
   EXPECT_EQ(kPeerAddress, connection_.peer_address());
   EXPECT_EQ(kPeerAddress, connection_.effective_peer_address());

   // Process another packet with a different peer address on server side will
   // start connection migration.
   const QuicSocketAddress kNewPeerAddress =
       QuicSocketAddress(QuicIpAddress::Loopback6(), /*port=*/23456);
   EXPECT_CALL(visitor_, OnConnectionMigration(PORT_CHANGE)).Times(1);
   ProcessFramePacketWithAddresses(frame, kSelfAddress, kNewPeerAddress);
   EXPECT_EQ(kNewPeerAddress, connection_.peer_address());
   EXPECT_EQ(kNewPeerAddress, connection_.effective_peer_address());
 }

 TEST_P(QuicConnectionTest, EffectivePeerAddressChangeAtServer) {
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
   set_perspective(Perspective::IS_SERVER);
   QuicPacketCreatorPeer::SetSendVersionInPacket(creator_, false);
   EXPECT_EQ(Perspective::IS_SERVER, connection_.perspective());

   // Clear direct_peer_address.
   QuicConnectionPeer::SetDirectPeerAddress(&connection_, QuicSocketAddress());
   // Clear effective_peer_address, it is different from direct_peer_address for
   // this test.
   QuicConnectionPeer::SetEffectivePeerAddress(&connection_,
                                               QuicSocketAddress());
   const QuicSocketAddress kEffectivePeerAddress =
       QuicSocketAddress(QuicIpAddress::Loopback6(), /*port=*/43210);
   connection_.ReturnEffectivePeerAddressForNextPacket(kEffectivePeerAddress);

   QuicFrame frame;
   if (QuicVersionUsesCryptoFrames(connection_.transport_version())) {
     frame = QuicFrame(&crypto_frame_);
     EXPECT_CALL(visitor_, OnCryptoFrame(_)).Times(AnyNumber());
   } else {
     frame = QuicFrame(QuicStreamFrame(
         QuicUtils::GetCryptoStreamId(connection_.transport_version()), false,
         0u, QuicStringPiece()));
     EXPECT_CALL(visitor_, OnStreamFrame(_)).Times(AnyNumber());
   }
   ProcessFramePacketWithAddresses(frame, kSelfAddress, kPeerAddress);
   EXPECT_EQ(kPeerAddress, connection_.peer_address());
   EXPECT_EQ(kEffectivePeerAddress, connection_.effective_peer_address());

   // Process another packet with the same direct peer address and different
   // effective peer address on server side will start connection migration.
   const QuicSocketAddress kNewEffectivePeerAddress =
       QuicSocketAddress(QuicIpAddress::Loopback6(), /*port=*/54321);
   connection_.ReturnEffectivePeerAddressForNextPacket(kNewEffectivePeerAddress);
   EXPECT_CALL(visitor_, OnConnectionMigration(PORT_CHANGE)).Times(1);
   ProcessFramePacketWithAddresses(frame, kSelfAddress, kPeerAddress);
   EXPECT_EQ(kPeerAddress, connection_.peer_address());
   EXPECT_EQ(kNewEffectivePeerAddress, connection_.effective_peer_address());

   // Process another packet with a different direct peer address and the same
   // effective peer address on server side will not start connection migration.
   const QuicSocketAddress kNewPeerAddress =
       QuicSocketAddress(QuicIpAddress::Loopback6(), /*port=*/23456);
   connection_.ReturnEffectivePeerAddressForNextPacket(kNewEffectivePeerAddress);
   EXPECT_CALL(visitor_, OnConnectionMigration(PORT_CHANGE)).Times(0);
   // ack_frame is used to complete the migration started by the last packet, we
   // need to make sure a new migration does not start after the previous one is
   // completed.
   QuicAckFrame ack_frame = InitAckFrame(1);
   EXPECT_CALL(*send_algorithm_, OnCongestionEvent(_, _, _, _, _));
   ProcessFramePacketWithAddresses(QuicFrame(&ack_frame), kSelfAddress,
                                   kNewPeerAddress);
   EXPECT_EQ(kNewPeerAddress, connection_.peer_address());
   EXPECT_EQ(kNewEffectivePeerAddress, connection_.effective_peer_address());

   // Process another packet with different direct peer address and different
   // effective peer address on server side will start connection migration.
   const QuicSocketAddress kNewerEffectivePeerAddress =
       QuicSocketAddress(QuicIpAddress::Loopback6(), /*port=*/65432);
   const QuicSocketAddress kFinalPeerAddress =
       QuicSocketAddress(QuicIpAddress::Loopback6(), /*port=*/34567);
   connection_.ReturnEffectivePeerAddressForNextPacket(
       kNewerEffectivePeerAddress);
   EXPECT_CALL(visitor_, OnConnectionMigration(PORT_CHANGE)).Times(1);
   ProcessFramePacketWithAddresses(frame, kSelfAddress, kFinalPeerAddress);
   EXPECT_EQ(kFinalPeerAddress, connection_.peer_address());
   EXPECT_EQ(kNewerEffectivePeerAddress, connection_.effective_peer_address());
   EXPECT_EQ(PORT_CHANGE, connection_.active_effective_peer_migration_type());

   // While the previous migration is ongoing, process another packet with the
   // same direct peer address and different effective peer address on server
   // side will start a new connection migration.
   const QuicSocketAddress kNewestEffectivePeerAddress =
       QuicSocketAddress(QuicIpAddress::Loopback4(), /*port=*/65430);
   connection_.ReturnEffectivePeerAddressForNextPacket(
       kNewestEffectivePeerAddress);
   EXPECT_CALL(visitor_, OnConnectionMigration(IPV6_TO_IPV4_CHANGE)).Times(1);
   EXPECT_CALL(*send_algorithm_, OnConnectionMigration()).Times(1);
   ProcessFramePacketWithAddresses(frame, kSelfAddress, kFinalPeerAddress);
   EXPECT_EQ(kFinalPeerAddress, connection_.peer_address());
   EXPECT_EQ(kNewestEffectivePeerAddress, connection_.effective_peer_address());
   EXPECT_EQ(IPV6_TO_IPV4_CHANGE,
             connection_.active_effective_peer_migration_type());
 }

 TEST_P(QuicConnectionTest, ReceivePaddedPingAtServer) {
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
   set_perspective(Perspective::IS_SERVER);
   QuicPacketCreatorPeer::SetSendVersionInPacket(creator_, false);
   EXPECT_EQ(Perspective::IS_SERVER, connection_.perspective());

   // Clear direct_peer_address.
   QuicConnectionPeer::SetDirectPeerAddress(&connection_, QuicSocketAddress());
   // Clear effective_peer_address, it is the same as direct_peer_address for
   // this test.
   QuicConnectionPeer::SetEffectivePeerAddress(&connection_,
                                               QuicSocketAddress());
   EXPECT_FALSE(connection_.effective_peer_address().IsInitialized());

   QuicFrame frame;
   if (QuicVersionUsesCryptoFrames(connection_.transport_version())) {
     frame = QuicFrame(&crypto_frame_);
     EXPECT_CALL(visitor_, OnCryptoFrame(_)).Times(AnyNumber());
   } else {
     frame = QuicFrame(QuicStreamFrame(
         QuicUtils::GetCryptoStreamId(connection_.transport_version()), false,
         0u, QuicStringPiece()));
     EXPECT_CALL(visitor_, OnStreamFrame(_)).Times(AnyNumber());
   }
   ProcessFramePacketWithAddresses(frame, kSelfAddress, kPeerAddress);
   EXPECT_EQ(kPeerAddress, connection_.peer_address());
   EXPECT_EQ(kPeerAddress, connection_.effective_peer_address());

   EXPECT_CALL(visitor_, OnConnectionMigration(PORT_CHANGE)).Times(0);
   EXPECT_CALL(visitor_, OnPacketReceived(_, _, false)).Times(0);

   // Process a padded PING or PATH CHALLENGE packet with no peer address change
   // on server side will be ignored.
   OwningSerializedPacketPointer probing_packet;
   if (VersionHasIetfQuicFrames(version().transport_version)) {
     QuicPathFrameBuffer payload = {
         {0xde, 0xad, 0xbe, 0xef, 0xba, 0xdc, 0x0f, 0xfe}};
     probing_packet =
         QuicPacketCreatorPeer::SerializePathChallengeConnectivityProbingPacket(
             &peer_creator_, &payload);
   } else {
     probing_packet = QuicPacketCreatorPeer::SerializeConnectivityProbingPacket(
         &peer_creator_);
   }
   std::unique_ptr<QuicReceivedPacket> received(ConstructReceivedPacket(
       QuicEncryptedPacket(probing_packet->encrypted_buffer,
                           probing_packet->encrypted_length),
       clock_.Now()));

   uint64_t num_probing_received =
       connection_.GetStats().num_connectivity_probing_received;
   ProcessReceivedPacket(kSelfAddress, kPeerAddress, *received);

   EXPECT_EQ(num_probing_received,
             connection_.GetStats().num_connectivity_probing_received);
   EXPECT_EQ(kPeerAddress, connection_.peer_address());
   EXPECT_EQ(kPeerAddress, connection_.effective_peer_address());
 }

 TEST_P(QuicConnectionTest, WriteOutOfOrderQueuedPackets) {
   // EXPECT_QUIC_BUG tests are expensive so only run one instance of them.
   if (!IsDefaultTestConfiguration()) {
     return;
   }

   set_perspective(Perspective::IS_CLIENT);

   BlockOnNextWrite();

   QuicStreamId stream_id = 2;
   connection_.SendStreamDataWithString(stream_id, "foo", 0, NO_FIN);

   EXPECT_EQ(1u, connection_.NumQueuedPackets());

   writer_->SetWritable();
   connection_.SendConnectivityProbingPacket(writer_.get(),
                                             connection_.peer_address());
   if (GetQuicReloadableFlag(quic_treat_queued_packets_as_sent)) {
     EXPECT_CALL(visitor_, OnConnectionClosed(_, _)).Times(0);
     connection_.OnCanWrite();
     return;
   }
   EXPECT_CALL(visitor_,
               OnConnectionClosed(_, ConnectionCloseSource::FROM_SELF));
   EXPECT_QUIC_BUG(connection_.OnCanWrite(),
                   "Attempt to write packet:1 after:2");
   EXPECT_FALSE(connection_.connected());
   TestConnectionCloseQuicErrorCode(QUIC_INTERNAL_ERROR);
   const std::vector<QuicConnectionCloseFrame>& connection_close_frames =
       writer_->connection_close_frames();
   EXPECT_EQ("Packet written out of order.",
             connection_close_frames[0].error_details);
 }

 TEST_P(QuicConnectionTest, DiscardQueuedPacketsAfterConnectionClose) {
   // Regression test for b/74073386.
   {
     InSequence seq;
     EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _))
         .Times(AtLeast(1));
     EXPECT_CALL(visitor_, OnConnectionClosed(_, _)).Times(AtLeast(1));
   }

   set_perspective(Perspective::IS_CLIENT);

   writer_->SimulateNextPacketTooLarge();

   // This packet write should fail, which should cause the connection to close
   // after sending a connection close packet, then the failed packet should be
   // queued.
   connection_.SendStreamDataWithString(/*id=*/2, "foo", 0, NO_FIN);

   EXPECT_FALSE(connection_.connected());
   if (GetQuicReloadableFlag(quic_treat_queued_packets_as_sent)) {
     // No need to buffer packets.
     EXPECT_EQ(0u, connection_.NumQueuedPackets());
   } else {
     EXPECT_EQ(1u, connection_.NumQueuedPackets());
   }

   EXPECT_EQ(0u, connection_.GetStats().packets_discarded);
   connection_.OnCanWrite();
   EXPECT_EQ(0u, connection_.GetStats().packets_discarded);
 }

 TEST_P(QuicConnectionTest, ReceiveConnectivityProbingAtServer) {
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
   set_perspective(Perspective::IS_SERVER);
   QuicPacketCreatorPeer::SetSendVersionInPacket(creator_, false);
   EXPECT_EQ(Perspective::IS_SERVER, connection_.perspective());

   // Clear direct_peer_address.
   QuicConnectionPeer::SetDirectPeerAddress(&connection_, QuicSocketAddress());
   // Clear effective_peer_address, it is the same as direct_peer_address for
   // this test.
   QuicConnectionPeer::SetEffectivePeerAddress(&connection_,
                                               QuicSocketAddress());
   EXPECT_FALSE(connection_.effective_peer_address().IsInitialized());

   QuicFrame frame;
   if (QuicVersionUsesCryptoFrames(connection_.transport_version())) {
     frame = QuicFrame(&crypto_frame_);
     EXPECT_CALL(visitor_, OnCryptoFrame(_)).Times(AnyNumber());
   } else {
     frame = QuicFrame(QuicStreamFrame(
         QuicUtils::GetCryptoStreamId(connection_.transport_version()), false,
         0u, QuicStringPiece()));
     EXPECT_CALL(visitor_, OnStreamFrame(_)).Times(AnyNumber());
   }
   ProcessFramePacketWithAddresses(frame, kSelfAddress, kPeerAddress);
   EXPECT_EQ(kPeerAddress, connection_.peer_address());
   EXPECT_EQ(kPeerAddress, connection_.effective_peer_address());

   EXPECT_CALL(visitor_, OnConnectionMigration(PORT_CHANGE)).Times(0);
   EXPECT_CALL(visitor_, OnPacketReceived(_, _, true)).Times(1);

   // Process a padded PING packet from a new peer address on server side
   // is effectively receiving a connectivity probing.
   const QuicSocketAddress kNewPeerAddress =
       QuicSocketAddress(QuicIpAddress::Loopback6(), /*port=*/23456);

   OwningSerializedPacketPointer probing_packet = ConstructProbingPacket();
   std::unique_ptr<QuicReceivedPacket> received(ConstructReceivedPacket(
       QuicEncryptedPacket(probing_packet->encrypted_buffer,
                           probing_packet->encrypted_length),
       clock_.Now()));

   uint64_t num_probing_received =
       connection_.GetStats().num_connectivity_probing_received;
   ProcessReceivedPacket(kSelfAddress, kNewPeerAddress, *received);

   EXPECT_EQ(num_probing_received + 1,
             connection_.GetStats().num_connectivity_probing_received);
   EXPECT_EQ(kPeerAddress, connection_.peer_address());
   EXPECT_EQ(kPeerAddress, connection_.effective_peer_address());

   // Process another packet with the old peer address on server side will not
   // start peer migration.
   EXPECT_CALL(visitor_, OnConnectionMigration(PORT_CHANGE)).Times(0);
   ProcessFramePacketWithAddresses(frame, kSelfAddress, kPeerAddress);
   EXPECT_EQ(kPeerAddress, connection_.peer_address());
   EXPECT_EQ(kPeerAddress, connection_.effective_peer_address());
 }

 TEST_P(QuicConnectionTest, ReceiveReorderedConnectivityProbingAtServer) {
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
   set_perspective(Perspective::IS_SERVER);
   QuicPacketCreatorPeer::SetSendVersionInPacket(creator_, false);
   EXPECT_EQ(Perspective::IS_SERVER, connection_.perspective());

   // Clear direct_peer_address.
   QuicConnectionPeer::SetDirectPeerAddress(&connection_, QuicSocketAddress());
   // Clear effective_peer_address, it is the same as direct_peer_address for
   // this test.
   QuicConnectionPeer::SetEffectivePeerAddress(&connection_,
                                               QuicSocketAddress());
   EXPECT_FALSE(connection_.effective_peer_address().IsInitialized());

   QuicFrame frame;
   if (QuicVersionUsesCryptoFrames(connection_.transport_version())) {
     frame = QuicFrame(&crypto_frame_);
     EXPECT_CALL(visitor_, OnCryptoFrame(_)).Times(AnyNumber());
   } else {
     frame = QuicFrame(QuicStreamFrame(
         QuicUtils::GetCryptoStreamId(connection_.transport_version()), false,
         0u, QuicStringPiece()));
     EXPECT_CALL(visitor_, OnStreamFrame(_)).Times(AnyNumber());
   }
   QuicPacketCreatorPeer::SetPacketNumber(&peer_creator_, 5);
   ProcessFramePacketWithAddresses(frame, kSelfAddress, kPeerAddress);
   EXPECT_EQ(kPeerAddress, connection_.peer_address());
   EXPECT_EQ(kPeerAddress, connection_.effective_peer_address());

   // Decrease packet number to simulate out-of-order packets.
   QuicPacketCreatorPeer::SetPacketNumber(&peer_creator_, 4);

   EXPECT_CALL(visitor_, OnConnectionMigration(PORT_CHANGE)).Times(0);
   EXPECT_CALL(visitor_, OnPacketReceived(_, _, true)).Times(1);

   // Process a padded PING packet from a new peer address on server side
   // is effectively receiving a connectivity probing, even if a newer packet has
   // been received before this one.
   const QuicSocketAddress kNewPeerAddress =
       QuicSocketAddress(QuicIpAddress::Loopback6(), /*port=*/23456);

   OwningSerializedPacketPointer probing_packet = ConstructProbingPacket();
   std::unique_ptr<QuicReceivedPacket> received(ConstructReceivedPacket(
       QuicEncryptedPacket(probing_packet->encrypted_buffer,
                           probing_packet->encrypted_length),
       clock_.Now()));

   uint64_t num_probing_received =
       connection_.GetStats().num_connectivity_probing_received;
   ProcessReceivedPacket(kSelfAddress, kNewPeerAddress, *received);

   EXPECT_EQ(num_probing_received + 1,
             connection_.GetStats().num_connectivity_probing_received);
   EXPECT_EQ(kPeerAddress, connection_.peer_address());
   EXPECT_EQ(kPeerAddress, connection_.effective_peer_address());
 }

 TEST_P(QuicConnectionTest, MigrateAfterProbingAtServer) {
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
   set_perspective(Perspective::IS_SERVER);
   QuicPacketCreatorPeer::SetSendVersionInPacket(creator_, false);
   EXPECT_EQ(Perspective::IS_SERVER, connection_.perspective());

   // Clear direct_peer_address.
   QuicConnectionPeer::SetDirectPeerAddress(&connection_, QuicSocketAddress());
   // Clear effective_peer_address, it is the same as direct_peer_address for
   // this test.
   QuicConnectionPeer::SetEffectivePeerAddress(&connection_,
                                               QuicSocketAddress());
   EXPECT_FALSE(connection_.effective_peer_address().IsInitialized());

   QuicFrame frame;
   if (QuicVersionUsesCryptoFrames(connection_.transport_version())) {
     frame = QuicFrame(&crypto_frame_);
     EXPECT_CALL(visitor_, OnCryptoFrame(_)).Times(AnyNumber());
   } else {
     frame = QuicFrame(QuicStreamFrame(
         QuicUtils::GetCryptoStreamId(connection_.transport_version()), false,
         0u, QuicStringPiece()));
     EXPECT_CALL(visitor_, OnStreamFrame(_)).Times(AnyNumber());
   }
   ProcessFramePacketWithAddresses(frame, kSelfAddress, kPeerAddress);
   EXPECT_EQ(kPeerAddress, connection_.peer_address());
   EXPECT_EQ(kPeerAddress, connection_.effective_peer_address());

   EXPECT_CALL(visitor_, OnConnectionMigration(PORT_CHANGE)).Times(0);
   EXPECT_CALL(visitor_, OnPacketReceived(_, _, true)).Times(1);

   // Process a padded PING packet from a new peer address on server side
   // is effectively receiving a connectivity probing.
   const QuicSocketAddress kNewPeerAddress =
       QuicSocketAddress(QuicIpAddress::Loopback6(), /*port=*/23456);

   OwningSerializedPacketPointer probing_packet = ConstructProbingPacket();
   std::unique_ptr<QuicReceivedPacket> received(ConstructReceivedPacket(
       QuicEncryptedPacket(probing_packet->encrypted_buffer,
                           probing_packet->encrypted_length),
       clock_.Now()));
   ProcessReceivedPacket(kSelfAddress, kNewPeerAddress, *received);
   EXPECT_EQ(kPeerAddress, connection_.peer_address());
   EXPECT_EQ(kPeerAddress, connection_.effective_peer_address());

   // Process another non-probing packet with the new peer address on server
   // side will start peer migration.
   EXPECT_CALL(visitor_, OnConnectionMigration(PORT_CHANGE)).Times(1);

   ProcessFramePacketWithAddresses(frame, kSelfAddress, kNewPeerAddress);
   EXPECT_EQ(kNewPeerAddress, connection_.peer_address());
   EXPECT_EQ(kNewPeerAddress, connection_.effective_peer_address());
 }

 TEST_P(QuicConnectionTest, ReceivePaddedPingAtClient) {
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
   set_perspective(Perspective::IS_CLIENT);
   EXPECT_EQ(Perspective::IS_CLIENT, connection_.perspective());

   // Clear direct_peer_address.
   QuicConnectionPeer::SetDirectPeerAddress(&connection_, QuicSocketAddress());
   // Clear effective_peer_address, it is the same as direct_peer_address for
   // this test.
   QuicConnectionPeer::SetEffectivePeerAddress(&connection_,
                                               QuicSocketAddress());
   EXPECT_FALSE(connection_.effective_peer_address().IsInitialized());

   QuicFrame frame;
   if (QuicVersionUsesCryptoFrames(connection_.transport_version())) {
     frame = QuicFrame(&crypto_frame_);
     EXPECT_CALL(visitor_, OnCryptoFrame(_)).Times(AnyNumber());
   } else {
     frame = QuicFrame(QuicStreamFrame(
         QuicUtils::GetCryptoStreamId(connection_.transport_version()), false,
         0u, QuicStringPiece()));
     EXPECT_CALL(visitor_, OnStreamFrame(_)).Times(AnyNumber());
   }
   ProcessFramePacketWithAddresses(frame, kSelfAddress, kPeerAddress);
   EXPECT_EQ(kPeerAddress, connection_.peer_address());
   EXPECT_EQ(kPeerAddress, connection_.effective_peer_address());

   // Client takes all padded PING packet as speculative connectivity
   // probing packet, and reports to visitor.
   EXPECT_CALL(visitor_, OnConnectionMigration(PORT_CHANGE)).Times(0);
   EXPECT_CALL(visitor_, OnPacketReceived(_, _, false)).Times(1);

   OwningSerializedPacketPointer probing_packet = ConstructProbingPacket();
   std::unique_ptr<QuicReceivedPacket> received(ConstructReceivedPacket(
       QuicEncryptedPacket(probing_packet->encrypted_buffer,
                           probing_packet->encrypted_length),
       clock_.Now()));
   uint64_t num_probing_received =
       connection_.GetStats().num_connectivity_probing_received;
   ProcessReceivedPacket(kSelfAddress, kPeerAddress, *received);

   EXPECT_EQ(num_probing_received,
             connection_.GetStats().num_connectivity_probing_received);
   EXPECT_EQ(kPeerAddress, connection_.peer_address());
   EXPECT_EQ(kPeerAddress, connection_.effective_peer_address());
 }

 TEST_P(QuicConnectionTest, ReceiveConnectivityProbingAtClient) {
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
   set_perspective(Perspective::IS_CLIENT);
   EXPECT_EQ(Perspective::IS_CLIENT, connection_.perspective());

   // Clear direct_peer_address.
   QuicConnectionPeer::SetDirectPeerAddress(&connection_, QuicSocketAddress());
   // Clear effective_peer_address, it is the same as direct_peer_address for
   // this test.
   QuicConnectionPeer::SetEffectivePeerAddress(&connection_,
                                               QuicSocketAddress());
   EXPECT_FALSE(connection_.effective_peer_address().IsInitialized());

   QuicFrame frame;
   if (QuicVersionUsesCryptoFrames(connection_.transport_version())) {
     frame = QuicFrame(&crypto_frame_);
     EXPECT_CALL(visitor_, OnCryptoFrame(_)).Times(AnyNumber());
   } else {
     frame = QuicFrame(QuicStreamFrame(
         QuicUtils::GetCryptoStreamId(connection_.transport_version()), false,
         0u, QuicStringPiece()));
     EXPECT_CALL(visitor_, OnStreamFrame(_)).Times(AnyNumber());
   }
   ProcessFramePacketWithAddresses(frame, kSelfAddress, kPeerAddress);
   EXPECT_EQ(kPeerAddress, connection_.peer_address());
   EXPECT_EQ(kPeerAddress, connection_.effective_peer_address());

   // Process a padded PING packet with a different self address on client side
   // is effectively receiving a connectivity probing.
   EXPECT_CALL(visitor_, OnConnectionMigration(PORT_CHANGE)).Times(0);
   EXPECT_CALL(visitor_, OnPacketReceived(_, _, true)).Times(1);

   const QuicSocketAddress kNewSelfAddress =
       QuicSocketAddress(QuicIpAddress::Loopback6(), /*port=*/23456);

   OwningSerializedPacketPointer probing_packet = ConstructProbingPacket();
   std::unique_ptr<QuicReceivedPacket> received(ConstructReceivedPacket(
       QuicEncryptedPacket(probing_packet->encrypted_buffer,
                           probing_packet->encrypted_length),
       clock_.Now()));
   uint64_t num_probing_received =
       connection_.GetStats().num_connectivity_probing_received;
   ProcessReceivedPacket(kNewSelfAddress, kPeerAddress, *received);

   EXPECT_EQ(num_probing_received + 1,
             connection_.GetStats().num_connectivity_probing_received);
   EXPECT_EQ(kPeerAddress, connection_.peer_address());
   EXPECT_EQ(kPeerAddress, connection_.effective_peer_address());
 }

 TEST_P(QuicConnectionTest, PeerAddressChangeAtClient) {
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
   set_perspective(Perspective::IS_CLIENT);
   EXPECT_EQ(Perspective::IS_CLIENT, connection_.perspective());

   // Clear direct_peer_address.
   QuicConnectionPeer::SetDirectPeerAddress(&connection_, QuicSocketAddress());
   // Clear effective_peer_address, it is the same as direct_peer_address for
   // this test.
   QuicConnectionPeer::SetEffectivePeerAddress(&connection_,
                                               QuicSocketAddress());
   EXPECT_FALSE(connection_.effective_peer_address().IsInitialized());

   QuicFrame frame;
   if (QuicVersionUsesCryptoFrames(connection_.transport_version())) {
     frame = QuicFrame(&crypto_frame_);
     EXPECT_CALL(visitor_, OnCryptoFrame(_)).Times(AnyNumber());
   } else {
     frame = QuicFrame(QuicStreamFrame(
         QuicUtils::GetCryptoStreamId(connection_.transport_version()), false,
         0u, QuicStringPiece()));
     EXPECT_CALL(visitor_, OnStreamFrame(_)).Times(AnyNumber());
   }
   ProcessFramePacketWithAddresses(frame, kSelfAddress, kPeerAddress);
   EXPECT_EQ(kPeerAddress, connection_.peer_address());
   EXPECT_EQ(kPeerAddress, connection_.effective_peer_address());

   // Process another packet with a different peer address on client side will
   // only update peer address.
   const QuicSocketAddress kNewPeerAddress =
       QuicSocketAddress(QuicIpAddress::Loopback6(), /*port=*/23456);
   EXPECT_CALL(visitor_, OnConnectionMigration(PORT_CHANGE)).Times(0);
   ProcessFramePacketWithAddresses(frame, kSelfAddress, kNewPeerAddress);
   EXPECT_EQ(kNewPeerAddress, connection_.peer_address());
   EXPECT_EQ(kNewPeerAddress, connection_.effective_peer_address());
 }

 TEST_P(QuicConnectionTest, MaxPacketSize) {
   EXPECT_EQ(Perspective::IS_CLIENT, connection_.perspective());
   EXPECT_EQ(1350u, connection_.max_packet_length());
 }

 TEST_P(QuicConnectionTest, SmallerServerMaxPacketSize) {
   TestConnection connection(TestConnectionId(), kPeerAddress, helper_.get(),
                             alarm_factory_.get(), writer_.get(),
                             Perspective::IS_SERVER, version());
   EXPECT_EQ(Perspective::IS_SERVER, connection.perspective());
   EXPECT_EQ(1000u, connection.max_packet_length());
 }

 TEST_P(QuicConnectionTest, IncreaseServerMaxPacketSize) {
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));

   set_perspective(Perspective::IS_SERVER);
   connection_.SetMaxPacketLength(1000);

   QuicPacketHeader header;
   header.destination_connection_id = connection_id_;
   header.version_flag = true;
   header.packet_number = QuicPacketNumber(12);

   if (QuicVersionHasLongHeaderLengths(
           peer_framer_.version().transport_version)) {
     header.long_packet_type = INITIAL;
     header.retry_token_length_length = VARIABLE_LENGTH_INTEGER_LENGTH_1;
     header.length_length = VARIABLE_LENGTH_INTEGER_LENGTH_2;
   }

   QuicFrames frames;
   QuicPaddingFrame padding;
   if (QuicVersionUsesCryptoFrames(connection_.transport_version())) {
     frames.push_back(QuicFrame(&crypto_frame_));
   } else {
     frames.push_back(QuicFrame(frame1_));
   }
   frames.push_back(QuicFrame(padding));
   std::unique_ptr<QuicPacket> packet(ConstructPacket(header, frames));
   char buffer[kMaxOutgoingPacketSize];
   size_t encrypted_length =
       peer_framer_.EncryptPayload(ENCRYPTION_INITIAL, QuicPacketNumber(12),
                                   *packet, buffer, kMaxOutgoingPacketSize);
   EXPECT_EQ(kMaxOutgoingPacketSize, encrypted_length);

   framer_.set_version(version());
   if (QuicVersionUsesCryptoFrames(connection_.transport_version())) {
     EXPECT_CALL(visitor_, OnCryptoFrame(_)).Times(1);
   } else {
     EXPECT_CALL(visitor_, OnStreamFrame(_)).Times(1);
   }
   connection_.ProcessUdpPacket(
       kSelfAddress, kPeerAddress,
       QuicReceivedPacket(buffer, encrypted_length, QuicTime::Zero(), false));

   EXPECT_EQ(kMaxOutgoingPacketSize, connection_.max_packet_length());
 }

 TEST_P(QuicConnectionTest, IncreaseServerMaxPacketSizeWhileWriterLimited) {
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));

   const QuicByteCount lower_max_packet_size = 1240;
   writer_->set_max_packet_size(lower_max_packet_size);
   set_perspective(Perspective::IS_SERVER);
   connection_.SetMaxPacketLength(1000);
   EXPECT_EQ(1000u, connection_.max_packet_length());

   QuicPacketHeader header;
   header.destination_connection_id = connection_id_;
   header.version_flag = true;
   header.packet_number = QuicPacketNumber(12);

   if (QuicVersionHasLongHeaderLengths(
           peer_framer_.version().transport_version)) {
     header.long_packet_type = INITIAL;
     header.retry_token_length_length = VARIABLE_LENGTH_INTEGER_LENGTH_1;
     header.length_length = VARIABLE_LENGTH_INTEGER_LENGTH_2;
   }

   QuicFrames frames;
   QuicPaddingFrame padding;
   if (QuicVersionUsesCryptoFrames(connection_.transport_version())) {
     frames.push_back(QuicFrame(&crypto_frame_));
   } else {
     frames.push_back(QuicFrame(frame1_));
   }
   frames.push_back(QuicFrame(padding));
   std::unique_ptr<QuicPacket> packet(ConstructPacket(header, frames));
   char buffer[kMaxOutgoingPacketSize];
   size_t encrypted_length =
       peer_framer_.EncryptPayload(ENCRYPTION_INITIAL, QuicPacketNumber(12),
                                   *packet, buffer, kMaxOutgoingPacketSize);
   EXPECT_EQ(kMaxOutgoingPacketSize, encrypted_length);

   framer_.set_version(version());
   if (QuicVersionUsesCryptoFrames(connection_.transport_version())) {
     EXPECT_CALL(visitor_, OnCryptoFrame(_)).Times(1);
   } else {
     EXPECT_CALL(visitor_, OnStreamFrame(_)).Times(1);
   }
   connection_.ProcessUdpPacket(
       kSelfAddress, kPeerAddress,
       QuicReceivedPacket(buffer, encrypted_length, QuicTime::Zero(), false));

   // Here, the limit imposed by the writer is lower than the size of the packet
   // received, so the writer max packet size is used.
   EXPECT_EQ(lower_max_packet_size, connection_.max_packet_length());
 }

 TEST_P(QuicConnectionTest, LimitMaxPacketSizeByWriter) {
   const QuicByteCount lower_max_packet_size = 1240;
   writer_->set_max_packet_size(lower_max_packet_size);

   static_assert(lower_max_packet_size < kDefaultMaxPacketSize,
                 "Default maximum packet size is too low");
   connection_.SetMaxPacketLength(kDefaultMaxPacketSize);

   EXPECT_EQ(lower_max_packet_size, connection_.max_packet_length());
 }

 TEST_P(QuicConnectionTest, LimitMaxPacketSizeByWriterForNewConnection) {
   const QuicConnectionId connection_id = TestConnectionId(17);
   const QuicByteCount lower_max_packet_size = 1240;
   writer_->set_max_packet_size(lower_max_packet_size);
   TestConnection connection(connection_id, kPeerAddress, helper_.get(),
                             alarm_factory_.get(), writer_.get(),
                             Perspective::IS_CLIENT, version());
   EXPECT_EQ(Perspective::IS_CLIENT, connection.perspective());
   EXPECT_EQ(lower_max_packet_size, connection.max_packet_length());
 }

 TEST_P(QuicConnectionTest, PacketsInOrder) {
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));

   ProcessPacket(1);
   EXPECT_EQ(QuicPacketNumber(1u), LargestAcked(connection_.ack_frame()));
   EXPECT_EQ(1u, connection_.ack_frame().packets.NumIntervals());

   ProcessPacket(2);
   EXPECT_EQ(QuicPacketNumber(2u), LargestAcked(connection_.ack_frame()));
   EXPECT_EQ(1u, connection_.ack_frame().packets.NumIntervals());

   ProcessPacket(3);
   EXPECT_EQ(QuicPacketNumber(3u), LargestAcked(connection_.ack_frame()));
   EXPECT_EQ(1u, connection_.ack_frame().packets.NumIntervals());
 }

 TEST_P(QuicConnectionTest, PacketsOutOfOrder) {
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));

   ProcessPacket(3);
   EXPECT_EQ(QuicPacketNumber(3u), LargestAcked(connection_.ack_frame()));
   EXPECT_TRUE(IsMissing(2));
   EXPECT_TRUE(IsMissing(1));

   ProcessPacket(2);
   EXPECT_EQ(QuicPacketNumber(3u), LargestAcked(connection_.ack_frame()));
   EXPECT_FALSE(IsMissing(2));
   EXPECT_TRUE(IsMissing(1));

   ProcessPacket(1);
   EXPECT_EQ(QuicPacketNumber(3u), LargestAcked(connection_.ack_frame()));
   EXPECT_FALSE(IsMissing(2));
   EXPECT_FALSE(IsMissing(1));
 }

 TEST_P(QuicConnectionTest, DuplicatePacket) {
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));

   ProcessPacket(3);
   EXPECT_EQ(QuicPacketNumber(3u), LargestAcked(connection_.ack_frame()));
   EXPECT_TRUE(IsMissing(2));
   EXPECT_TRUE(IsMissing(1));

   // Send packet 3 again, but do not set the expectation that
   // the visitor OnStreamFrame() will be called.
   ProcessDataPacket(3);
   EXPECT_EQ(QuicPacketNumber(3u), LargestAcked(connection_.ack_frame()));
   EXPECT_TRUE(IsMissing(2));
   EXPECT_TRUE(IsMissing(1));
 }

 TEST_P(QuicConnectionTest, PacketsOutOfOrderWithAdditionsAndLeastAwaiting) {
   if (connection_.SupportsMultiplePacketNumberSpaces()) {
     return;
   }
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));

   ProcessPacket(3);
   EXPECT_EQ(QuicPacketNumber(3u), LargestAcked(connection_.ack_frame()));
   EXPECT_TRUE(IsMissing(2));
   EXPECT_TRUE(IsMissing(1));

   ProcessPacket(2);
   EXPECT_EQ(QuicPacketNumber(3u), LargestAcked(connection_.ack_frame()));
   EXPECT_TRUE(IsMissing(1));

   ProcessPacket(5);
   EXPECT_EQ(QuicPacketNumber(5u), LargestAcked(connection_.ack_frame()));
   EXPECT_TRUE(IsMissing(1));
   EXPECT_TRUE(IsMissing(4));

   // Pretend at this point the client has gotten acks for 2 and 3 and 1 is a
   // packet the peer will not retransmit.  It indicates this by sending 'least
   // awaiting' is 4.  The connection should then realize 1 will not be
   // retransmitted, and will remove it from the missing list.
   QuicAckFrame frame = InitAckFrame(1);
   EXPECT_CALL(*send_algorithm_, OnCongestionEvent(_, _, _, _, _));
   ProcessAckPacket(6, &frame);

   // Force an ack to be sent.
   SendAckPacketToPeer();
   EXPECT_TRUE(IsMissing(4));
 }

 TEST_P(QuicConnectionTest, RejectUnencryptedStreamData) {
   // EXPECT_QUIC_BUG tests are expensive so only run one instance of them.
   if (!IsDefaultTestConfiguration()) {
     return;
   }

   // Process an unencrypted packet from the non-crypto stream.
   frame1_.stream_id = 3;
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
   EXPECT_CALL(visitor_,
               OnConnectionClosed(_, ConnectionCloseSource::FROM_SELF));
   EXPECT_QUIC_PEER_BUG(ProcessDataPacketAtLevel(1, false, ENCRYPTION_INITIAL),
                        "");
   TestConnectionCloseQuicErrorCode(QUIC_UNENCRYPTED_STREAM_DATA);
 }

 TEST_P(QuicConnectionTest, OutOfOrderReceiptCausesAckSend) {
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));

   ProcessPacket(3);
   // Should not cause an ack.
   EXPECT_EQ(0u, writer_->packets_write_attempts());

   ProcessPacket(2);
   // Should ack immediately, since this fills the last hole.
   EXPECT_EQ(1u, writer_->packets_write_attempts());

   ProcessPacket(1);
   // Should ack immediately, since this fills the last hole.
   EXPECT_EQ(2u, writer_->packets_write_attempts());

   ProcessPacket(4);
   // Should not cause an ack.
   EXPECT_EQ(2u, writer_->packets_write_attempts());
 }

 TEST_P(QuicConnectionTest, OutOfOrderAckReceiptCausesNoAck) {
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));

   SendStreamDataToPeer(1, "foo", 0, NO_FIN, nullptr);
   SendStreamDataToPeer(1, "bar", 3, NO_FIN, nullptr);
   EXPECT_EQ(2u, writer_->packets_write_attempts());

   QuicAckFrame ack1 = InitAckFrame(1);
   QuicAckFrame ack2 = InitAckFrame(2);
   EXPECT_CALL(*send_algorithm_, OnCongestionEvent(true, _, _, _, _));
   ProcessAckPacket(2, &ack2);
   // Should ack immediately since we have missing packets.
   EXPECT_EQ(2u, writer_->packets_write_attempts());

   ProcessAckPacket(1, &ack1);
   // Should not ack an ack filling a missing packet.
   EXPECT_EQ(2u, writer_->packets_write_attempts());
 }

 TEST_P(QuicConnectionTest, AckReceiptCausesAckSend) {
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
   QuicPacketNumber original, second;

   QuicByteCount packet_size =
       SendStreamDataToPeer(3, "foo", 0, NO_FIN, &original);  // 1st packet.
   SendStreamDataToPeer(3, "bar", 3, NO_FIN, &second);        // 2nd packet.

   QuicAckFrame frame = InitAckFrame({{second, second + 1}});
   // First nack triggers early retransmit.
   LostPacketVector lost_packets;
   lost_packets.push_back(LostPacket(original, kMaxOutgoingPacketSize));
   EXPECT_CALL(*loss_algorithm_, DetectLosses(_, _, _, _, _, _))
       .WillOnce(SetArgPointee<5>(lost_packets));
   EXPECT_CALL(*send_algorithm_, OnCongestionEvent(true, _, _, _, _));
   QuicPacketNumber retransmission;
   // Packet 1 is short header for IETF QUIC because the encryption level
   // switched to ENCRYPTION_FORWARD_SECURE in SendStreamDataToPeer.
   EXPECT_CALL(*send_algorithm_,
               OnPacketSent(_, _, _,
                            VersionHasIetfInvariantHeader(
                                GetParam().version.transport_version)
                                ? packet_size
                                : packet_size - kQuicVersionSize,
                            _))
       .WillOnce(SaveArg<2>(&retransmission));

   ProcessAckPacket(&frame);

   QuicAckFrame frame2 = ConstructAckFrame(retransmission, original);
   EXPECT_CALL(*send_algorithm_, OnCongestionEvent(true, _, _, _, _));
   EXPECT_CALL(*loss_algorithm_, DetectLosses(_, _, _, _, _, _));
   ProcessAckPacket(&frame2);

   // Now if the peer sends an ack which still reports the retransmitted packet
   // as missing, that will bundle an ack with data after two acks in a row
   // indicate the high water mark needs to be raised.
   EXPECT_CALL(*send_algorithm_,
               OnPacketSent(_, _, _, _, HAS_RETRANSMITTABLE_DATA));
   connection_.SendStreamDataWithString(3, "foo", 6, NO_FIN);
   // No ack sent.
   size_t padding_frame_count = writer_->padding_frames().size();
   EXPECT_EQ(padding_frame_count + 1u, writer_->frame_count());
   EXPECT_EQ(1u, writer_->stream_frames().size());

   // No more packet loss for the rest of the test.
   EXPECT_CALL(*loss_algorithm_, DetectLosses(_, _, _, _, _, _))
       .Times(AnyNumber());
   ProcessAckPacket(&frame2);
   EXPECT_CALL(*send_algorithm_,
               OnPacketSent(_, _, _, _, HAS_RETRANSMITTABLE_DATA));
   connection_.SendStreamDataWithString(3, "foofoofoo", 9, NO_FIN);
   // Ack bundled.
   if (GetParam().no_stop_waiting) {
     if (GetQuicReloadableFlag(quic_simplify_stop_waiting)) {
       // Do not ACK acks.
       EXPECT_EQ(1u, writer_->frame_count());
     } else {
       EXPECT_EQ(2u, writer_->frame_count());
     }
   } else {
     EXPECT_EQ(3u, writer_->frame_count());
   }
   EXPECT_EQ(1u, writer_->stream_frames().size());
   if (GetParam().no_stop_waiting &&
       GetQuicReloadableFlag(quic_simplify_stop_waiting)) {
     EXPECT_TRUE(writer_->ack_frames().empty());
   } else {
     EXPECT_FALSE(writer_->ack_frames().empty());
   }

   // But an ack with no missing packets will not send an ack.
   AckPacket(original, &frame2);
   ProcessAckPacket(&frame2);
   ProcessAckPacket(&frame2);
 }

 TEST_P(QuicConnectionTest, AckSentEveryNthPacket) {
   connection_.set_ack_frequency_before_ack_decimation(3);

   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
   EXPECT_CALL(visitor_, OnStreamFrame(_)).Times(39);

   // Expect 13 acks, every 3rd packet.
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(13);
   // Receives packets 1 - 39.
   for (size_t i = 1; i <= 39; ++i) {
     ProcessDataPacket(i);
   }
 }

 TEST_P(QuicConnectionTest, AckDecimationReducesAcks) {
   const size_t kMinRttMs = 40;
   RttStats* rtt_stats = const_cast<RttStats*>(manager_->GetRttStats());
   rtt_stats->UpdateRtt(QuicTime::Delta::FromMilliseconds(kMinRttMs),
                        QuicTime::Delta::Zero(), QuicTime::Zero());
   EXPECT_CALL(visitor_, OnAckNeedsRetransmittableFrame()).Times(AnyNumber());

   QuicConnectionPeer::SetAckMode(&connection_, ACK_DECIMATION_WITH_REORDERING);

   // Start ack decimation from 10th packet.
   connection_.set_min_received_before_ack_decimation(10);

   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
   EXPECT_CALL(visitor_, OnStreamFrame(_)).Times(30);

   // Expect 6 acks: 5 acks between packets 1-10, and ack at 20.
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(6);
   // Receives packets 1 - 29.
   for (size_t i = 1; i <= 29; ++i) {
     ProcessDataPacket(i);
   }

   // We now receive the 30th packet, and so we send an ack.
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(1);
   ProcessDataPacket(30);
 }

 TEST_P(QuicConnectionTest, AckNeedsRetransmittableFrames) {
   connection_.SetDefaultEncryptionLevel(ENCRYPTION_FORWARD_SECURE);
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
   EXPECT_CALL(visitor_, OnStreamFrame(_)).Times(99);

   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(19);
   // Receives packets 1 - 39.
   for (size_t i = 1; i <= 39; ++i) {
     ProcessDataPacket(i);
   }
   // Receiving Packet 40 causes 20th ack to send. Session is informed and adds
   // WINDOW_UPDATE.
   EXPECT_CALL(visitor_, OnAckNeedsRetransmittableFrame())
       .WillOnce(Invoke([this]() {
         connection_.SendControlFrame(
             QuicFrame(new QuicWindowUpdateFrame(1, 0, 0)));
       }));
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(1);
   EXPECT_EQ(0u, writer_->window_update_frames().size());
   ProcessDataPacket(40);
   EXPECT_EQ(1u, writer_->window_update_frames().size());

   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(9);
   // Receives packets 41 - 59.
   for (size_t i = 41; i <= 59; ++i) {
     ProcessDataPacket(i);
   }
   // Send a packet containing stream frame.
   SendStreamDataToPeer(
       QuicUtils::GetFirstBidirectionalStreamId(
           connection_.version().transport_version, Perspective::IS_CLIENT),
       "bar", 0, NO_FIN, nullptr);

   // Session will not be informed until receiving another 20 packets.
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(19);
   for (size_t i = 60; i <= 98; ++i) {
     ProcessDataPacket(i);
     EXPECT_EQ(0u, writer_->window_update_frames().size());
   }
   // Session does not add a retransmittable frame.
   EXPECT_CALL(visitor_, OnAckNeedsRetransmittableFrame())
       .WillOnce(Invoke([this]() {
         connection_.SendControlFrame(QuicFrame(QuicPingFrame(1)));
       }));
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(1);
   EXPECT_EQ(0u, writer_->ping_frames().size());
   ProcessDataPacket(99);
   EXPECT_EQ(0u, writer_->window_update_frames().size());
   // A ping frame will be added.
   EXPECT_EQ(1u, writer_->ping_frames().size());
 }

 TEST_P(QuicConnectionTest, LeastUnackedLower) {
   if (VersionHasIetfInvariantHeader(GetParam().version.transport_version)) {
     return;
   }
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));

   SendStreamDataToPeer(1, "foo", 0, NO_FIN, nullptr);
   SendStreamDataToPeer(1, "bar", 3, NO_FIN, nullptr);
   SendStreamDataToPeer(1, "eep", 6, NO_FIN, nullptr);

   // Start out saying the least unacked is 2.
   QuicPacketCreatorPeer::SetPacketNumber(&peer_creator_, 5);
   ProcessStopWaitingPacket(InitStopWaitingFrame(2));

   // Change it to 1, but lower the packet number to fake out-of-order packets.
   // This should be fine.
   QuicPacketCreatorPeer::SetPacketNumber(&peer_creator_, 1);
   // The scheduler will not process out of order acks, but all packet processing
   // causes the connection to try to write.
   if (!GetParam().no_stop_waiting) {
     EXPECT_CALL(visitor_, OnCanWrite());
   }
   ProcessStopWaitingPacket(InitStopWaitingFrame(1));

   // Now claim it's one, but set the ordering so it was sent "after" the first
   // one.  This should cause a connection error.
   QuicPacketCreatorPeer::SetPacketNumber(&peer_creator_, 7);
   if (!GetParam().no_stop_waiting) {
     EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _))
         .Times(AtLeast(1));
     EXPECT_CALL(visitor_,
                 OnConnectionClosed(_, ConnectionCloseSource::FROM_SELF))
         .Times(AtLeast(1));
   }
   ProcessStopWaitingPacket(InitStopWaitingFrame(1));
   if (!GetParam().no_stop_waiting) {
     TestConnectionCloseQuicErrorCode(QUIC_INVALID_STOP_WAITING_DATA);
   }
 }

 TEST_P(QuicConnectionTest, TooManySentPackets) {
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));

   QuicPacketCount max_tracked_packets = 50;
   QuicConnectionPeer::SetMaxTrackedPackets(&connection_, max_tracked_packets);

   const int num_packets = max_tracked_packets + 5;

   for (int i = 0; i < num_packets; ++i) {
     SendStreamDataToPeer(1, "foo", 3 * i, NO_FIN, nullptr);
   }

   // Ack packet 1, which leaves more than the limit outstanding.
   EXPECT_CALL(*send_algorithm_, OnCongestionEvent(true, _, _, _, _));
   EXPECT_CALL(visitor_,
               OnConnectionClosed(_, ConnectionCloseSource::FROM_SELF));

   // Nack the first packet and ack the rest, leaving a huge gap.
   QuicAckFrame frame1 = ConstructAckFrame(num_packets, 1);
   ProcessAckPacket(&frame1);
   TestConnectionCloseQuicErrorCode(QUIC_TOO_MANY_OUTSTANDING_SENT_PACKETS);
 }

 TEST_P(QuicConnectionTest, LargestObservedLower) {
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));

   SendStreamDataToPeer(1, "foo", 0, NO_FIN, nullptr);
   SendStreamDataToPeer(1, "bar", 3, NO_FIN, nullptr);
   SendStreamDataToPeer(1, "eep", 6, NO_FIN, nullptr);
   EXPECT_CALL(*send_algorithm_, OnCongestionEvent(true, _, _, _, _));

   // Start out saying the largest observed is 2.
   QuicAckFrame frame1 = InitAckFrame(1);
   QuicAckFrame frame2 = InitAckFrame(2);
   ProcessAckPacket(&frame2);

   EXPECT_CALL(visitor_, OnCanWrite());
   ProcessAckPacket(&frame1);
 }

 TEST_P(QuicConnectionTest, AckUnsentData) {
   // Ack a packet which has not been sent.
   EXPECT_CALL(visitor_,
               OnConnectionClosed(_, ConnectionCloseSource::FROM_SELF));
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(AtLeast(1));
   QuicAckFrame frame = InitAckFrame(1);
   EXPECT_CALL(visitor_, OnCanWrite()).Times(0);
   ProcessAckPacket(&frame);
   TestConnectionCloseQuicErrorCode(QUIC_INVALID_ACK_DATA);
 }

 TEST_P(QuicConnectionTest, BasicSending) {
   if (connection_.SupportsMultiplePacketNumberSpaces()) {
     return;
   }
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
   EXPECT_CALL(visitor_, OnStreamFrame(_)).Times(1);
   ProcessDataPacket(1);
   QuicPacketCreatorPeer::SetPacketNumber(&peer_creator_, 2);
   QuicPacketNumber last_packet;
   SendStreamDataToPeer(1, "foo", 0, NO_FIN, &last_packet);  // Packet 1
   EXPECT_EQ(QuicPacketNumber(1u), last_packet);
   SendAckPacketToPeer();  // Packet 2

   if (GetParam().no_stop_waiting) {
     // Expect no stop waiting frame is sent.
     EXPECT_FALSE(least_unacked().IsInitialized());
   } else {
     EXPECT_EQ(QuicPacketNumber(1u), least_unacked());
   }

   SendAckPacketToPeer();  // Packet 3
   if (GetParam().no_stop_waiting) {
     // Expect no stop waiting frame is sent.
     EXPECT_FALSE(least_unacked().IsInitialized());
   } else {
     EXPECT_EQ(QuicPacketNumber(1u), least_unacked());
   }

   SendStreamDataToPeer(1, "bar", 3, NO_FIN, &last_packet);  // Packet 4
   EXPECT_EQ(QuicPacketNumber(4u), last_packet);
   SendAckPacketToPeer();  // Packet 5
   if (GetParam().no_stop_waiting) {
     // Expect no stop waiting frame is sent.
     EXPECT_FALSE(least_unacked().IsInitialized());
   } else {
     EXPECT_EQ(QuicPacketNumber(1u), least_unacked());
   }

   EXPECT_CALL(*send_algorithm_, OnCongestionEvent(true, _, _, _, _));

   // Peer acks up to packet 3.
   QuicAckFrame frame = InitAckFrame(3);
   ProcessAckPacket(&frame);
   SendAckPacketToPeer();  // Packet 6

   // As soon as we've acked one, we skip ack packets 2 and 3 and note lack of
   // ack for 4.
   if (GetParam().no_stop_waiting) {
     // Expect no stop waiting frame is sent.
     EXPECT_FALSE(least_unacked().IsInitialized());
   } else {
     EXPECT_EQ(QuicPacketNumber(4u), least_unacked());
   }

   EXPECT_CALL(*send_algorithm_, OnCongestionEvent(true, _, _, _, _));

   // Peer acks up to packet 4, the last packet.
   QuicAckFrame frame2 = InitAckFrame(6);
   ProcessAckPacket(&frame2);  // Acks don't instigate acks.

   // Verify that we did not send an ack.
   EXPECT_EQ(QuicPacketNumber(6u), writer_->header().packet_number);

   // So the last ack has not changed.
   if (GetParam().no_stop_waiting) {
     // Expect no stop waiting frame is sent.
     EXPECT_FALSE(least_unacked().IsInitialized());
   } else {
     EXPECT_EQ(QuicPacketNumber(4u), least_unacked());
   }

   // If we force an ack, we shouldn't change our retransmit state.
   SendAckPacketToPeer();  // Packet 7
   if (GetParam().no_stop_waiting) {
     // Expect no stop waiting frame is sent.
     EXPECT_FALSE(least_unacked().IsInitialized());
   } else {
     EXPECT_EQ(QuicPacketNumber(7u), least_unacked());
   }

   // But if we send more data it should.
   SendStreamDataToPeer(1, "eep", 6, NO_FIN, &last_packet);  // Packet 8
   EXPECT_EQ(QuicPacketNumber(8u), last_packet);
   SendAckPacketToPeer();  // Packet 9
   if (GetParam().no_stop_waiting) {
     // Expect no stop waiting frame is sent.
     EXPECT_FALSE(least_unacked().IsInitialized());
   } else {
     EXPECT_EQ(QuicPacketNumber(7u), least_unacked());
   }
 }

 // QuicConnection should record the packet sent-time prior to sending the
 // packet.
 TEST_P(QuicConnectionTest, RecordSentTimeBeforePacketSent) {
   // We're using a MockClock for the tests, so we have complete control over the
   // time.
   // Our recorded timestamp for the last packet sent time will be passed in to
   // the send_algorithm.  Make sure that it is set to the correct value.
   QuicTime actual_recorded_send_time = QuicTime::Zero();
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _))
       .WillOnce(SaveArg<0>(&actual_recorded_send_time));

   // First send without any pause and check the result.
   QuicTime expected_recorded_send_time = clock_.Now();
   connection_.SendStreamDataWithString(1, "foo", 0, NO_FIN);
   EXPECT_EQ(expected_recorded_send_time, actual_recorded_send_time)
       << "Expected time = " << expected_recorded_send_time.ToDebuggingValue()
       << ".  Actual time = " << actual_recorded_send_time.ToDebuggingValue();

   // Now pause during the write, and check the results.
   actual_recorded_send_time = QuicTime::Zero();
   const QuicTime::Delta write_pause_time_delta =
       QuicTime::Delta::FromMilliseconds(5000);
   SetWritePauseTimeDelta(write_pause_time_delta);
   expected_recorded_send_time = clock_.Now();

   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _))
       .WillOnce(SaveArg<0>(&actual_recorded_send_time));
   connection_.SendStreamDataWithString(2, "baz", 0, NO_FIN);
   EXPECT_EQ(expected_recorded_send_time, actual_recorded_send_time)
       << "Expected time = " << expected_recorded_send_time.ToDebuggingValue()
       << ".  Actual time = " << actual_recorded_send_time.ToDebuggingValue();
 }

 TEST_P(QuicConnectionTest, FramePacking) {
   // Send two stream frames in 1 packet by queueing them.
   connection_.SetDefaultEncryptionLevel(ENCRYPTION_FORWARD_SECURE);
   {
     QuicConnection::ScopedPacketFlusher flusher(&connection_);
     connection_.SendStreamData3();
     connection_.SendStreamData5();
     EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(1);
   }
   EXPECT_EQ(0u, connection_.NumQueuedPackets());
   EXPECT_FALSE(connection_.HasQueuedData());

   // Parse the last packet and ensure it's an ack and two stream frames from
   // two different streams.
   if (GetParam().no_stop_waiting) {
     EXPECT_EQ(2u, writer_->frame_count());
     EXPECT_TRUE(writer_->stop_waiting_frames().empty());
   } else {
     EXPECT_EQ(2u, writer_->frame_count());
     EXPECT_TRUE(writer_->stop_waiting_frames().empty());
   }

   EXPECT_TRUE(writer_->ack_frames().empty());

   ASSERT_EQ(2u, writer_->stream_frames().size());
   EXPECT_EQ(GetNthClientInitiatedStreamId(1, connection_.transport_version()),
             writer_->stream_frames()[0]->stream_id);
   EXPECT_EQ(GetNthClientInitiatedStreamId(2, connection_.transport_version()),
             writer_->stream_frames()[1]->stream_id);
 }

 TEST_P(QuicConnectionTest, FramePackingNonCryptoThenCrypto) {
   // Send two stream frames (one non-crypto, then one crypto) in 2 packets by
   // queueing them.
   connection_.SetDefaultEncryptionLevel(ENCRYPTION_FORWARD_SECURE);
   {
     EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(2);
     QuicConnection::ScopedPacketFlusher flusher(&connection_);
     connection_.SendStreamData3();
     connection_.SendCryptoStreamData();
   }
   EXPECT_EQ(0u, connection_.NumQueuedPackets());
   EXPECT_FALSE(connection_.HasQueuedData());

   // Parse the last packet and ensure it's the crypto stream frame.
   EXPECT_EQ(2u, writer_->frame_count());
   ASSERT_EQ(1u, writer_->padding_frames().size());
   if (!QuicVersionUsesCryptoFrames(connection_.transport_version())) {
     ASSERT_EQ(1u, writer_->stream_frames().size());
     EXPECT_EQ(QuicUtils::GetCryptoStreamId(connection_.transport_version()),
               writer_->stream_frames()[0]->stream_id);
   } else {
     EXPECT_EQ(1u, writer_->crypto_frames().size());
   }
 }

 TEST_P(QuicConnectionTest, FramePackingCryptoThenNonCrypto) {
   // Send two stream frames (one crypto, then one non-crypto) in 2 packets by
   // queueing them.
   {
     connection_.SetDefaultEncryptionLevel(ENCRYPTION_FORWARD_SECURE);
     EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(2);
     QuicConnection::ScopedPacketFlusher flusher(&connection_);
     connection_.SendCryptoStreamData();
     connection_.SendStreamData3();
   }
   EXPECT_EQ(0u, connection_.NumQueuedPackets());
   EXPECT_FALSE(connection_.HasQueuedData());

   // Parse the last packet and ensure it's the stream frame from stream 3.
   size_t padding_frame_count = writer_->padding_frames().size();
   EXPECT_EQ(padding_frame_count + 1u, writer_->frame_count());
   ASSERT_EQ(1u, writer_->stream_frames().size());
   EXPECT_EQ(GetNthClientInitiatedStreamId(1, connection_.transport_version()),
             writer_->stream_frames()[0]->stream_id);
 }

 TEST_P(QuicConnectionTest, FramePackingAckResponse) {
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
   // Process a data packet to queue up a pending ack.
   if (QuicVersionUsesCryptoFrames(connection_.transport_version())) {
     EXPECT_CALL(visitor_, OnCryptoFrame(_)).Times(1);
   } else {
     EXPECT_CALL(visitor_, OnStreamFrame(_)).Times(1);
   }
   ProcessCryptoPacketAtLevel(1, ENCRYPTION_INITIAL);

   QuicPacketNumber last_packet;
   if (QuicVersionUsesCryptoFrames(connection_.transport_version())) {
     connection_.SendCryptoDataWithString("foo", 0);
   } else {
     SendStreamDataToPeer(
         QuicUtils::GetCryptoStreamId(connection_.transport_version()), "foo", 0,
         NO_FIN, &last_packet);
   }
   // Verify ack is bundled with outging packet.
   EXPECT_FALSE(writer_->ack_frames().empty());

   EXPECT_CALL(visitor_, OnCanWrite())
       .WillOnce(DoAll(IgnoreResult(InvokeWithoutArgs(
                           &connection_, &TestConnection::SendStreamData3)),
                       IgnoreResult(InvokeWithoutArgs(
                           &connection_, &TestConnection::SendStreamData5))));

   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(1);

   // Process a data packet to cause the visitor's OnCanWrite to be invoked.
   EXPECT_CALL(visitor_, OnStreamFrame(_)).Times(1);
   peer_framer_.SetEncrypter(ENCRYPTION_FORWARD_SECURE,
                             std::make_unique<TaggingEncrypter>(0x01));
   SetDecrypter(ENCRYPTION_FORWARD_SECURE,
                std::make_unique<StrictTaggingDecrypter>(0x01));
   ProcessDataPacket(2);

   EXPECT_EQ(0u, connection_.NumQueuedPackets());
   EXPECT_FALSE(connection_.HasQueuedData());

   // Parse the last packet and ensure it's an ack and two stream frames from
   // two different streams.
   if (GetParam().no_stop_waiting) {
     EXPECT_EQ(3u, writer_->frame_count());
     EXPECT_TRUE(writer_->stop_waiting_frames().empty());
   } else {
     EXPECT_EQ(4u, writer_->frame_count());
     EXPECT_FALSE(writer_->stop_waiting_frames().empty());
   }
   EXPECT_FALSE(writer_->ack_frames().empty());
   ASSERT_EQ(2u, writer_->stream_frames().size());
   EXPECT_EQ(GetNthClientInitiatedStreamId(1, connection_.transport_version()),
             writer_->stream_frames()[0]->stream_id);
   EXPECT_EQ(GetNthClientInitiatedStreamId(2, connection_.transport_version()),
             writer_->stream_frames()[1]->stream_id);
 }

 TEST_P(QuicConnectionTest, FramePackingSendv) {
   connection_.SetDefaultEncryptionLevel(ENCRYPTION_FORWARD_SECURE);
   // Send data in 1 packet by writing multiple blocks in a single iovector
   // using writev.
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _));

   char data[] = "ABCDEF";
   struct iovec iov[2];
   iov[0].iov_base = data;
   iov[0].iov_len = 4;
   iov[1].iov_base = data + 4;
   iov[1].iov_len = 2;
   QuicStreamId stream_id = QuicUtils::GetFirstBidirectionalStreamId(
       connection_.transport_version(), Perspective::IS_CLIENT);
   connection_.SaveAndSendStreamData(stream_id, iov, 2, 6, 0, NO_FIN);

   EXPECT_EQ(0u, connection_.NumQueuedPackets());
   EXPECT_FALSE(connection_.HasQueuedData());

   // Parse the last packet and ensure multiple iovector blocks have
   // been packed into a single stream frame from one stream.
   EXPECT_EQ(1u, writer_->frame_count());
   EXPECT_EQ(1u, writer_->stream_frames().size());
   EXPECT_EQ(0u, writer_->padding_frames().size());
   QuicStreamFrame* frame = writer_->stream_frames()[0].get();
   EXPECT_EQ(stream_id, frame->stream_id);
   EXPECT_EQ("ABCDEF", QuicStringPiece(frame->data_buffer, frame->data_length));
 }

 TEST_P(QuicConnectionTest, FramePackingSendvQueued) {
   connection_.SetDefaultEncryptionLevel(ENCRYPTION_FORWARD_SECURE);
   // Try to send two stream frames in 1 packet by using writev.
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _));

   BlockOnNextWrite();
   char data[] = "ABCDEF";
   struct iovec iov[2];
   iov[0].iov_base = data;
   iov[0].iov_len = 4;
   iov[1].iov_base = data + 4;
   iov[1].iov_len = 2;
   QuicStreamId stream_id = QuicUtils::GetFirstBidirectionalStreamId(
       connection_.transport_version(), Perspective::IS_CLIENT);
   connection_.SaveAndSendStreamData(stream_id, iov, 2, 6, 0, NO_FIN);

   EXPECT_EQ(1u, connection_.NumQueuedPackets());
   EXPECT_TRUE(connection_.HasQueuedData());

   // Unblock the writes and actually send.
   writer_->SetWritable();
   connection_.OnCanWrite();
   EXPECT_EQ(0u, connection_.NumQueuedPackets());

   // Parse the last packet and ensure it's one stream frame from one stream.
   EXPECT_EQ(1u, writer_->frame_count());
   EXPECT_EQ(1u, writer_->stream_frames().size());
   EXPECT_EQ(0u, writer_->padding_frames().size());
   EXPECT_EQ(stream_id, writer_->stream_frames()[0]->stream_id);
 }

 TEST_P(QuicConnectionTest, SendingZeroBytes) {
   connection_.SetDefaultEncryptionLevel(ENCRYPTION_FORWARD_SECURE);
   // Send a zero byte write with a fin using writev.
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _));
   QuicStreamId stream_id = QuicUtils::GetFirstBidirectionalStreamId(
       connection_.transport_version(), Perspective::IS_CLIENT);
   connection_.SaveAndSendStreamData(stream_id, nullptr, 0, 0, 0, FIN);

   EXPECT_EQ(0u, connection_.NumQueuedPackets());
   EXPECT_FALSE(connection_.HasQueuedData());

   // Padding frames are added by v99 to ensure a minimum packet size.
   size_t extra_padding_frames = 0;
   if (GetParam().version.HasHeaderProtection()) {
     extra_padding_frames = 1;
   }

   // Parse the last packet and ensure it's one stream frame from one stream.
   EXPECT_EQ(1u + extra_padding_frames, writer_->frame_count());
   EXPECT_EQ(extra_padding_frames, writer_->padding_frames().size());
   ASSERT_EQ(1u, writer_->stream_frames().size());
   EXPECT_EQ(stream_id, writer_->stream_frames()[0]->stream_id);
   EXPECT_TRUE(writer_->stream_frames()[0]->fin);
 }

 TEST_P(QuicConnectionTest, LargeSendWithPendingAck) {
   connection_.SetDefaultEncryptionLevel(ENCRYPTION_FORWARD_SECURE);
   // Set the ack alarm by processing a ping frame.
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));

   // Processs a PING frame.
   ProcessFramePacket(QuicFrame(QuicPingFrame()));
   // Ensure that this has caused the ACK alarm to be set.
   QuicAlarm* ack_alarm = QuicConnectionPeer::GetAckAlarm(&connection_);
   EXPECT_TRUE(ack_alarm->IsSet());

   // Send data and ensure the ack is bundled.
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(8);
   size_t len = 10000;
   std::unique_ptr<char[]> data_array(new char[len]);
   memset(data_array.get(), '?', len);
   struct iovec iov;
   iov.iov_base = data_array.get();
   iov.iov_len = len;
   QuicConsumedData consumed = connection_.SaveAndSendStreamData(
       GetNthClientInitiatedStreamId(0, connection_.transport_version()), &iov,
       1, len, 0, FIN);
   EXPECT_EQ(len, consumed.bytes_consumed);
   EXPECT_TRUE(consumed.fin_consumed);
   EXPECT_EQ(0u, connection_.NumQueuedPackets());
   EXPECT_FALSE(connection_.HasQueuedData());

   // Parse the last packet and ensure it's one stream frame with a fin.
   EXPECT_EQ(1u, writer_->frame_count());
   ASSERT_EQ(1u, writer_->stream_frames().size());
   EXPECT_EQ(GetNthClientInitiatedStreamId(0, connection_.transport_version()),
             writer_->stream_frames()[0]->stream_id);
   EXPECT_TRUE(writer_->stream_frames()[0]->fin);
   // Ensure the ack alarm was cancelled when the ack was sent.
   EXPECT_FALSE(ack_alarm->IsSet());
 }

 TEST_P(QuicConnectionTest, OnCanWrite) {
   // Visitor's OnCanWrite will send data, but will have more pending writes.
   EXPECT_CALL(visitor_, OnCanWrite())
       .WillOnce(DoAll(IgnoreResult(InvokeWithoutArgs(
                           &connection_, &TestConnection::SendStreamData3)),
                       IgnoreResult(InvokeWithoutArgs(
                           &connection_, &TestConnection::SendStreamData5))));
   {
     InSequence seq;
     EXPECT_CALL(visitor_, WillingAndAbleToWrite()).WillOnce(Return(true));
     EXPECT_CALL(visitor_, WillingAndAbleToWrite())
         .WillRepeatedly(Return(false));
   }

   EXPECT_CALL(*send_algorithm_, CanSend(_))
       .WillRepeatedly(testing::Return(true));

   connection_.OnCanWrite();

   // Parse the last packet and ensure it's the two stream frames from
   // two different streams.
   EXPECT_EQ(2u, writer_->frame_count());
   EXPECT_EQ(2u, writer_->stream_frames().size());
   EXPECT_EQ(GetNthClientInitiatedStreamId(1, connection_.transport_version()),
             writer_->stream_frames()[0]->stream_id);
   EXPECT_EQ(GetNthClientInitiatedStreamId(2, connection_.transport_version()),
             writer_->stream_frames()[1]->stream_id);
 }

 TEST_P(QuicConnectionTest, RetransmitOnNack) {
   QuicPacketNumber last_packet;
   QuicByteCount second_packet_size;
   SendStreamDataToPeer(3, "foo", 0, NO_FIN, &last_packet);  // Packet 1
   second_packet_size =
       SendStreamDataToPeer(3, "foos", 3, NO_FIN, &last_packet);  // Packet 2
   SendStreamDataToPeer(3, "fooos", 7, NO_FIN, &last_packet);     // Packet 3

   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));

   // Don't lose a packet on an ack, and nothing is retransmitted.
   EXPECT_CALL(*send_algorithm_, OnCongestionEvent(true, _, _, _, _));
   QuicAckFrame ack_one = InitAckFrame(1);
   ProcessAckPacket(&ack_one);

   // Lose a packet and ensure it triggers retransmission.
   QuicAckFrame nack_two = ConstructAckFrame(3, 2);
   LostPacketVector lost_packets;
   lost_packets.push_back(
       LostPacket(QuicPacketNumber(2), kMaxOutgoingPacketSize));
   EXPECT_CALL(*loss_algorithm_, DetectLosses(_, _, _, _, _, _))
       .WillOnce(SetArgPointee<5>(lost_packets));
   EXPECT_CALL(*send_algorithm_, OnCongestionEvent(true, _, _, _, _));
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(1);
   EXPECT_FALSE(QuicPacketCreatorPeer::SendVersionInPacket(creator_));
   ProcessAckPacket(&nack_two);
 }

 TEST_P(QuicConnectionTest, DoNotSendQueuedPacketForResetStream) {
   // Block the connection to queue the packet.
   BlockOnNextWrite();

   QuicStreamId stream_id = 2;
   connection_.SendStreamDataWithString(stream_id, "foo", 0, NO_FIN);

   // Now that there is a queued packet, reset the stream.
   SendRstStream(stream_id, QUIC_ERROR_PROCESSING_STREAM, 3);

   // Unblock the connection and verify that only the RST_STREAM is sent.
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(1);
   writer_->SetWritable();
   connection_.OnCanWrite();
   if (!connection_.session_decides_what_to_write()) {
     // OnCanWrite will cause RST_STREAM be sent again.
     connection_.SendControlFrame(QuicFrame(new QuicRstStreamFrame(
         1, stream_id, QUIC_ERROR_PROCESSING_STREAM, 14)));
   }
   size_t padding_frame_count = writer_->padding_frames().size();
   EXPECT_EQ(padding_frame_count + 1u, writer_->frame_count());
   EXPECT_EQ(1u, writer_->rst_stream_frames().size());
 }

 TEST_P(QuicConnectionTest, SendQueuedPacketForQuicRstStreamNoError) {
   // Block the connection to queue the packet.
   BlockOnNextWrite();

   QuicStreamId stream_id = 2;
   if (GetQuicReloadableFlag(quic_treat_queued_packets_as_sent)) {
     EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(1);
   } else {
     EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(0);
   }
   connection_.SendStreamDataWithString(stream_id, "foo", 0, NO_FIN);

   // Now that there is a queued packet, reset the stream.
   SendRstStream(stream_id, QUIC_STREAM_NO_ERROR, 3);

   // Unblock the connection and verify that the RST_STREAM is sent and the data
   // packet is sent.
   if (GetQuicReloadableFlag(quic_treat_queued_packets_as_sent)) {
     EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _))
         .Times(AtLeast(1));
   } else {
     EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _))
         .Times(AtLeast(2));
   }
   writer_->SetWritable();
   connection_.OnCanWrite();
   if (!connection_.session_decides_what_to_write()) {
     // OnCanWrite will cause RST_STREAM be sent again.
     connection_.SendControlFrame(QuicFrame(
         new QuicRstStreamFrame(1, stream_id, QUIC_STREAM_NO_ERROR, 14)));
   }
   size_t padding_frame_count = writer_->padding_frames().size();
   EXPECT_EQ(padding_frame_count + 1u, writer_->frame_count());
   EXPECT_EQ(1u, writer_->rst_stream_frames().size());
 }

 TEST_P(QuicConnectionTest, DoNotRetransmitForResetStreamOnNack) {
   QuicStreamId stream_id = 2;
   QuicPacketNumber last_packet;
   SendStreamDataToPeer(stream_id, "foo", 0, NO_FIN, &last_packet);
   SendStreamDataToPeer(stream_id, "foos", 3, NO_FIN, &last_packet);
   SendStreamDataToPeer(stream_id, "fooos", 7, NO_FIN, &last_packet);

   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(1);
   SendRstStream(stream_id, QUIC_ERROR_PROCESSING_STREAM, 12);

   // Lose a packet and ensure it does not trigger retransmission.
   QuicAckFrame nack_two = ConstructAckFrame(last_packet, last_packet - 1);
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
   EXPECT_CALL(*loss_algorithm_, DetectLosses(_, _, _, _, _, _));
   EXPECT_CALL(*send_algorithm_, OnCongestionEvent(true, _, _, _, _));
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(0);
   ProcessAckPacket(&nack_two);
 }

 TEST_P(QuicConnectionTest, RetransmitForQuicRstStreamNoErrorOnNack) {
   QuicStreamId stream_id = 2;
   QuicPacketNumber last_packet;
   SendStreamDataToPeer(stream_id, "foo", 0, NO_FIN, &last_packet);
   SendStreamDataToPeer(stream_id, "foos", 3, NO_FIN, &last_packet);
   SendStreamDataToPeer(stream_id, "fooos", 7, NO_FIN, &last_packet);

   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(1);
   SendRstStream(stream_id, QUIC_STREAM_NO_ERROR, 12);

   // Lose a packet, ensure it triggers retransmission.
   QuicAckFrame nack_two = ConstructAckFrame(last_packet, last_packet - 1);
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
   LostPacketVector lost_packets;
   lost_packets.push_back(LostPacket(last_packet - 1, kMaxOutgoingPacketSize));
   EXPECT_CALL(*loss_algorithm_, DetectLosses(_, _, _, _, _, _))
       .WillOnce(SetArgPointee<5>(lost_packets));
   EXPECT_CALL(*send_algorithm_, OnCongestionEvent(true, _, _, _, _));
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(AtLeast(1));
   ProcessAckPacket(&nack_two);
 }

 TEST_P(QuicConnectionTest, DoNotRetransmitForResetStreamOnRTO) {
   QuicStreamId stream_id = 2;
   QuicPacketNumber last_packet;
   SendStreamDataToPeer(stream_id, "foo", 0, NO_FIN, &last_packet);

   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(1);
   SendRstStream(stream_id, QUIC_ERROR_PROCESSING_STREAM, 3);

   // Fire the RTO and verify that the RST_STREAM is resent, not stream data.
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(1);
   clock_.AdvanceTime(DefaultRetransmissionTime());
   connection_.GetRetransmissionAlarm()->Fire();
   size_t padding_frame_count = writer_->padding_frames().size();
   EXPECT_EQ(padding_frame_count + 1u, writer_->frame_count());
   EXPECT_EQ(1u, writer_->rst_stream_frames().size());
   EXPECT_EQ(stream_id, writer_->rst_stream_frames().front().stream_id);
 }

 // Ensure that if the only data in flight is non-retransmittable, the
 // retransmission alarm is not set.
 TEST_P(QuicConnectionTest, CancelRetransmissionAlarmAfterResetStream) {
   QuicStreamId stream_id = 2;
   QuicPacketNumber last_data_packet;
   SendStreamDataToPeer(stream_id, "foo", 0, NO_FIN, &last_data_packet);

   // Cancel the stream.
   const QuicPacketNumber rst_packet = last_data_packet + 1;
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, rst_packet, _, _)).Times(1);
   SendRstStream(stream_id, QUIC_ERROR_PROCESSING_STREAM, 3);

   // Ack the RST_STREAM frame (since it's retransmittable), but not the data
   // packet, which is no longer retransmittable since the stream was cancelled.
   QuicAckFrame nack_stream_data =
       ConstructAckFrame(rst_packet, last_data_packet);
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
   EXPECT_CALL(*send_algorithm_, OnCongestionEvent(true, _, _, _, _));
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(0);
   ProcessAckPacket(&nack_stream_data);

   // Ensure that the data is still in flight, but the retransmission alarm is no
   // longer set.
   EXPECT_GT(manager_->GetBytesInFlight(), 0u);
   if (connection_.session_decides_what_to_write()) {
     EXPECT_TRUE(connection_.GetRetransmissionAlarm()->IsSet());
   } else {
     EXPECT_FALSE(connection_.GetRetransmissionAlarm()->IsSet());
   }
 }

 TEST_P(QuicConnectionTest, RetransmitForQuicRstStreamNoErrorOnRTO) {
   connection_.SetMaxTailLossProbes(0);

   QuicStreamId stream_id = 2;
   QuicPacketNumber last_packet;
   SendStreamDataToPeer(stream_id, "foo", 0, NO_FIN, &last_packet);

   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(1);
   SendRstStream(stream_id, QUIC_STREAM_NO_ERROR, 3);

   // Fire the RTO and verify that the RST_STREAM is resent, the stream data
   // is sent.
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(AtLeast(2));
   clock_.AdvanceTime(DefaultRetransmissionTime());
   connection_.GetRetransmissionAlarm()->Fire();
   size_t padding_frame_count = writer_->padding_frames().size();
   EXPECT_EQ(padding_frame_count + 1u, writer_->frame_count());
   ASSERT_EQ(1u, writer_->rst_stream_frames().size());
   EXPECT_EQ(stream_id, writer_->rst_stream_frames().front().stream_id);
 }

 TEST_P(QuicConnectionTest, DoNotSendPendingRetransmissionForResetStream) {
   QuicStreamId stream_id = 2;
   QuicPacketNumber last_packet;
   SendStreamDataToPeer(stream_id, "foo", 0, NO_FIN, &last_packet);
   SendStreamDataToPeer(stream_id, "foos", 3, NO_FIN, &last_packet);
   BlockOnNextWrite();
   connection_.SendStreamDataWithString(stream_id, "fooos", 7, NO_FIN);

   // Lose a packet which will trigger a pending retransmission.
   QuicAckFrame ack = ConstructAckFrame(last_packet, last_packet - 1);
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
   EXPECT_CALL(*loss_algorithm_, DetectLosses(_, _, _, _, _, _));
   EXPECT_CALL(*send_algorithm_, OnCongestionEvent(true, _, _, _, _));
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(0);
   ProcessAckPacket(&ack);

   SendRstStream(stream_id, QUIC_ERROR_PROCESSING_STREAM, 12);

   // Unblock the connection and verify that the RST_STREAM is sent but not the
   // second data packet nor a retransmit.
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(1);
   writer_->SetWritable();
   connection_.OnCanWrite();
   if (!connection_.session_decides_what_to_write()) {
     // OnCanWrite will cause this RST_STREAM_FRAME be sent again.
     connection_.SendControlFrame(QuicFrame(new QuicRstStreamFrame(
         1, stream_id, QUIC_ERROR_PROCESSING_STREAM, 14)));
   }
   size_t padding_frame_count = writer_->padding_frames().size();
   EXPECT_EQ(padding_frame_count + 1u, writer_->frame_count());
   ASSERT_EQ(1u, writer_->rst_stream_frames().size());
   EXPECT_EQ(stream_id, writer_->rst_stream_frames().front().stream_id);
 }

 TEST_P(QuicConnectionTest, SendPendingRetransmissionForQuicRstStreamNoError) {
   QuicStreamId stream_id = 2;
   QuicPacketNumber last_packet;
   SendStreamDataToPeer(stream_id, "foo", 0, NO_FIN, &last_packet);
   SendStreamDataToPeer(stream_id, "foos", 3, NO_FIN, &last_packet);
   BlockOnNextWrite();
   connection_.SendStreamDataWithString(stream_id, "fooos", 7, NO_FIN);

   // Lose a packet which will trigger a pending retransmission.
   QuicAckFrame ack = ConstructAckFrame(last_packet, last_packet - 1);
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
   LostPacketVector lost_packets;
   lost_packets.push_back(LostPacket(last_packet - 1, kMaxOutgoingPacketSize));
   EXPECT_CALL(*loss_algorithm_, DetectLosses(_, _, _, _, _, _))
       .WillOnce(SetArgPointee<5>(lost_packets));
   EXPECT_CALL(*send_algorithm_, OnCongestionEvent(true, _, _, _, _));
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(0);
   ProcessAckPacket(&ack);

   SendRstStream(stream_id, QUIC_STREAM_NO_ERROR, 12);

   // Unblock the connection and verify that the RST_STREAM is sent and the
   // second data packet or a retransmit is sent.
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(AtLeast(2));
   writer_->SetWritable();
   connection_.OnCanWrite();
   // The RST_STREAM_FRAME is sent after queued packets and pending
   // retransmission.
   connection_.SendControlFrame(QuicFrame(
       new QuicRstStreamFrame(1, stream_id, QUIC_STREAM_NO_ERROR, 14)));
   size_t padding_frame_count = writer_->padding_frames().size();
   EXPECT_EQ(padding_frame_count + 1u, writer_->frame_count());
   EXPECT_EQ(1u, writer_->rst_stream_frames().size());
 }

 TEST_P(QuicConnectionTest, RetransmitAckedPacket) {
   QuicPacketNumber last_packet;
   SendStreamDataToPeer(1, "foo", 0, NO_FIN, &last_packet);    // Packet 1
   SendStreamDataToPeer(1, "foos", 3, NO_FIN, &last_packet);   // Packet 2
   SendStreamDataToPeer(1, "fooos", 7, NO_FIN, &last_packet);  // Packet 3

   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));

   // Instigate a loss with an ack.
   QuicAckFrame nack_two = ConstructAckFrame(3, 2);
   // The first nack should trigger a fast retransmission, but we'll be
   // write blocked, so the packet will be queued.
   BlockOnNextWrite();

   LostPacketVector lost_packets;
   lost_packets.push_back(
       LostPacket(QuicPacketNumber(2), kMaxOutgoingPacketSize));
   EXPECT_CALL(*loss_algorithm_, DetectLosses(_, _, _, _, _, _))
       .WillOnce(SetArgPointee<5>(lost_packets));
   EXPECT_CALL(*send_algorithm_, OnCongestionEvent(true, _, _, _, _));
   if (GetQuicReloadableFlag(quic_treat_queued_packets_as_sent)) {
     EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, QuicPacketNumber(4), _, _))
         .Times(1);
   } else {
     EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(0);
   }
   ProcessAckPacket(&nack_two);
   EXPECT_EQ(1u, connection_.NumQueuedPackets());

   // Now, ack the previous transmission.
   EXPECT_CALL(*loss_algorithm_, DetectLosses(_, _, _, _, _, _));
   EXPECT_CALL(*send_algorithm_, OnCongestionEvent(false, _, _, _, _));
   QuicAckFrame ack_all = InitAckFrame(3);
   ProcessAckPacket(&ack_all);

   if (GetQuicReloadableFlag(quic_treat_queued_packets_as_sent)) {
     EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, QuicPacketNumber(4), _, _))
         .Times(0);
   } else {
     // Unblock the socket and attempt to send the queued packets. We will always
     // send the retransmission.
     EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, QuicPacketNumber(4), _, _))
         .Times(1);
   }

   writer_->SetWritable();
   connection_.OnCanWrite();

   EXPECT_EQ(0u, connection_.NumQueuedPackets());
   // We do not store retransmittable frames of this retransmission.
   EXPECT_FALSE(QuicConnectionPeer::HasRetransmittableFrames(&connection_, 4));
 }

 TEST_P(QuicConnectionTest, RetransmitNackedLargestObserved) {
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
   QuicPacketNumber original, second;

   QuicByteCount packet_size =
       SendStreamDataToPeer(3, "foo", 0, NO_FIN, &original);  // 1st packet.
   SendStreamDataToPeer(3, "bar", 3, NO_FIN, &second);        // 2nd packet.

   QuicAckFrame frame = InitAckFrame({{second, second + 1}});
   // The first nack should retransmit the largest observed packet.
   LostPacketVector lost_packets;
   lost_packets.push_back(LostPacket(original, kMaxOutgoingPacketSize));
   EXPECT_CALL(*loss_algorithm_, DetectLosses(_, _, _, _, _, _))
       .WillOnce(SetArgPointee<5>(lost_packets));
   EXPECT_CALL(*send_algorithm_, OnCongestionEvent(true, _, _, _, _));
   // Packet 1 is short header for IETF QUIC because the encryption level
   // switched to ENCRYPTION_FORWARD_SECURE in SendStreamDataToPeer.
   EXPECT_CALL(*send_algorithm_,
               OnPacketSent(_, _, _,
                            VersionHasIetfInvariantHeader(
                                GetParam().version.transport_version)
                                ? packet_size
                                : packet_size - kQuicVersionSize,
                            _));
   ProcessAckPacket(&frame);
 }

 TEST_P(QuicConnectionTest, QueueAfterTwoRTOs) {
   if (connection_.PtoEnabled() ||
       !connection_.session_decides_what_to_write()) {
     return;
   }
   connection_.SetMaxTailLossProbes(0);

   for (int i = 0; i < 10; ++i) {
     EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(1);
     connection_.SendStreamDataWithString(3, "foo", i * 3, NO_FIN);
   }

   // Block the writer and ensure they're queued.
   BlockOnNextWrite();
   clock_.AdvanceTime(DefaultRetransmissionTime());
   if (GetQuicReloadableFlag(quic_treat_queued_packets_as_sent)) {
     EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(2);
   } else {
     EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(0);
   }
   connection_.GetRetransmissionAlarm()->Fire();
   EXPECT_TRUE(connection_.HasQueuedData());

   // Unblock the writer.
   writer_->SetWritable();
   clock_.AdvanceTime(QuicTime::Delta::FromMicroseconds(
       2 * DefaultRetransmissionTime().ToMicroseconds()));
   if (GetQuicReloadableFlag(quic_treat_queued_packets_as_sent)) {
     EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(2);
   } else {
     // 2 RTOs + 1 TLP, which is buggy.
     EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(3);
   }
   connection_.GetRetransmissionAlarm()->Fire();
   connection_.OnCanWrite();
 }

 TEST_P(QuicConnectionTest, WriteBlockedBufferedThenSent) {
   BlockOnNextWrite();
   writer_->set_is_write_blocked_data_buffered(true);
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(1);
   connection_.SendStreamDataWithString(1, "foo", 0, NO_FIN);
   EXPECT_TRUE(connection_.GetRetransmissionAlarm()->IsSet());

   writer_->SetWritable();
   connection_.OnCanWrite();
   EXPECT_TRUE(connection_.GetRetransmissionAlarm()->IsSet());
 }

 TEST_P(QuicConnectionTest, WriteBlockedThenSent) {
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(0);
   BlockOnNextWrite();
   if (GetQuicReloadableFlag(quic_treat_queued_packets_as_sent)) {
     EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(1);
   } else {
     EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(0);
   }
   connection_.SendStreamDataWithString(1, "foo", 0, NO_FIN);
   if (GetQuicReloadableFlag(quic_treat_queued_packets_as_sent)) {
     EXPECT_TRUE(connection_.GetRetransmissionAlarm()->IsSet());
   } else {
     EXPECT_FALSE(connection_.GetRetransmissionAlarm()->IsSet());
   }
   EXPECT_EQ(1u, connection_.NumQueuedPackets());

   // The second packet should also be queued, in order to ensure packets are
   // never sent out of order.
   writer_->SetWritable();
   if (GetQuicReloadableFlag(quic_treat_queued_packets_as_sent)) {
     EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(1);
   } else {
     EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(0);
   }
   connection_.SendStreamDataWithString(1, "foo", 0, NO_FIN);
   EXPECT_EQ(2u, connection_.NumQueuedPackets());

   // Now both are sent in order when we unblock.
   if (GetQuicReloadableFlag(quic_treat_queued_packets_as_sent)) {
     EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(0);
   } else {
     EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(2);
   }
   connection_.OnCanWrite();
   EXPECT_TRUE(connection_.GetRetransmissionAlarm()->IsSet());
   EXPECT_EQ(0u, connection_.NumQueuedPackets());
 }

 TEST_P(QuicConnectionTest, RetransmitWriteBlockedAckedOriginalThenSent) {
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
   connection_.SendStreamDataWithString(3, "foo", 0, NO_FIN);
   EXPECT_TRUE(connection_.GetRetransmissionAlarm()->IsSet());

   BlockOnNextWrite();
   writer_->set_is_write_blocked_data_buffered(true);
   // Simulate the retransmission alarm firing.
   clock_.AdvanceTime(DefaultRetransmissionTime());
   connection_.GetRetransmissionAlarm()->Fire();

   // Ack the sent packet before the callback returns, which happens in
   // rare circumstances with write blocked sockets.
   QuicAckFrame ack = InitAckFrame(1);
   EXPECT_CALL(*send_algorithm_, OnCongestionEvent(true, _, _, _, _));
   ProcessAckPacket(&ack);

   writer_->SetWritable();
   connection_.OnCanWrite();
   if (connection_.session_decides_what_to_write()) {
     EXPECT_TRUE(connection_.GetRetransmissionAlarm()->IsSet());
   } else {
     EXPECT_FALSE(connection_.GetRetransmissionAlarm()->IsSet());
   }
   EXPECT_FALSE(QuicConnectionPeer::HasRetransmittableFrames(&connection_, 2));
 }

 TEST_P(QuicConnectionTest, AlarmsWhenWriteBlocked) {
   // Block the connection.
   BlockOnNextWrite();
   connection_.SendStreamDataWithString(3, "foo", 0, NO_FIN);
   EXPECT_EQ(1u, writer_->packets_write_attempts());
   EXPECT_TRUE(writer_->IsWriteBlocked());

   // Set the send alarm. Fire the alarm and ensure it doesn't attempt to write.
   connection_.GetSendAlarm()->Set(clock_.ApproximateNow());
   connection_.GetSendAlarm()->Fire();
   EXPECT_TRUE(writer_->IsWriteBlocked());
   EXPECT_EQ(1u, writer_->packets_write_attempts());
 }

 TEST_P(QuicConnectionTest, NoSendAlarmAfterProcessPacketWhenWriteBlocked) {
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));

   // Block the connection.
   BlockOnNextWrite();
   connection_.SendStreamDataWithString(3, "foo", 0, NO_FIN);
   EXPECT_TRUE(writer_->IsWriteBlocked());
   EXPECT_EQ(1u, connection_.NumQueuedPackets());
   EXPECT_FALSE(connection_.GetSendAlarm()->IsSet());

   EXPECT_CALL(visitor_, OnStreamFrame(_)).Times(1);
   // Process packet number 1. Can not call ProcessPacket or ProcessDataPacket
   // here, because they will fire the alarm after QuicConnection::ProcessPacket
   // is returned.
   const uint64_t received_packet_num = 1;
   const bool has_stop_waiting = false;
   const EncryptionLevel level = ENCRYPTION_FORWARD_SECURE;
   std::unique_ptr<QuicPacket> packet(
       ConstructDataPacket(received_packet_num, has_stop_waiting, level));
   char buffer[kMaxOutgoingPacketSize];
   size_t encrypted_length =
       peer_framer_.EncryptPayload(level, QuicPacketNumber(received_packet_num),
                                   *packet, buffer, kMaxOutgoingPacketSize);
   connection_.ProcessUdpPacket(
       kSelfAddress, kPeerAddress,
       QuicReceivedPacket(buffer, encrypted_length, clock_.Now(), false));

   EXPECT_TRUE(writer_->IsWriteBlocked());
   EXPECT_FALSE(connection_.GetSendAlarm()->IsSet());
 }

 TEST_P(QuicConnectionTest, AddToWriteBlockedListIfWriterBlockedWhenProcessing) {
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
   SendStreamDataToPeer(1, "foo", 0, NO_FIN, nullptr);

   // Simulate the case where a shared writer gets blocked by another connection.
   writer_->SetWriteBlocked();

   // Process an ACK, make sure the connection calls visitor_->OnWriteBlocked().
   QuicAckFrame ack1 = InitAckFrame(1);
   EXPECT_CALL(*send_algorithm_, OnCongestionEvent(_, _, _, _, _));
   EXPECT_CALL(visitor_, OnWriteBlocked()).Times(1);
   ProcessAckPacket(1, &ack1);
 }

 TEST_P(QuicConnectionTest, DoNotAddToWriteBlockedListAfterDisconnect) {
   writer_->SetBatchMode(true);
   EXPECT_TRUE(connection_.connected());
   // Have to explicitly grab the OnConnectionClosed frame and check
   // its parameters because this is a silent connection close and the
   // frame is not also transmitted to the peer.
   EXPECT_CALL(visitor_, OnConnectionClosed(_, ConnectionCloseSource::FROM_SELF))
       .WillOnce(Invoke(this, &QuicConnectionTest::SaveConnectionCloseFrame));

   EXPECT_CALL(visitor_, OnWriteBlocked()).Times(0);

   {
     QuicConnection::ScopedPacketFlusher flusher(&connection_);
     connection_.CloseConnection(QUIC_PEER_GOING_AWAY, "no reason",
                                 ConnectionCloseBehavior::SILENT_CLOSE);

     EXPECT_FALSE(connection_.connected());
     writer_->SetWriteBlocked();
   }
   EXPECT_EQ(1, connection_close_frame_count_);
   EXPECT_EQ(QUIC_PEER_GOING_AWAY,
             saved_connection_close_frame_.quic_error_code);
 }

 TEST_P(QuicConnectionTest, AddToWriteBlockedListIfBlockedOnFlushPackets) {
   writer_->SetBatchMode(true);
   writer_->BlockOnNextFlush();

   EXPECT_CALL(visitor_, OnWriteBlocked()).Times(1);
   {
     QuicConnection::ScopedPacketFlusher flusher(&connection_);
     // flusher's destructor will call connection_.FlushPackets, which should add
     // the connection to the write blocked list.
   }
 }

 TEST_P(QuicConnectionTest, NoLimitPacketsPerNack) {
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
   int offset = 0;
   // Send packets 1 to 15.
   for (int i = 0; i < 15; ++i) {
     SendStreamDataToPeer(1, "foo", offset, NO_FIN, nullptr);
     offset += 3;
   }

   // Ack 15, nack 1-14.

   QuicAckFrame nack =
       InitAckFrame({{QuicPacketNumber(15), QuicPacketNumber(16)}});

   // 14 packets have been NACK'd and lost.
   LostPacketVector lost_packets;
   for (int i = 1; i < 15; ++i) {
     lost_packets.push_back(
         LostPacket(QuicPacketNumber(i), kMaxOutgoingPacketSize));
   }
   EXPECT_CALL(*loss_algorithm_, DetectLosses(_, _, _, _, _, _))
       .WillOnce(SetArgPointee<5>(lost_packets));
   EXPECT_CALL(*send_algorithm_, OnCongestionEvent(true, _, _, _, _));
   if (connection_.session_decides_what_to_write()) {
     EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(1);
   } else {
     EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(14);
   }
   ProcessAckPacket(&nack);
 }

 // Test sending multiple acks from the connection to the session.
 TEST_P(QuicConnectionTest, MultipleAcks) {
   if (connection_.SupportsMultiplePacketNumberSpaces()) {
     return;
   }
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
   EXPECT_CALL(visitor_, OnStreamFrame(_)).Times(1);
   ProcessDataPacket(1);
   QuicPacketCreatorPeer::SetPacketNumber(&peer_creator_, 2);
   QuicPacketNumber last_packet;
   SendStreamDataToPeer(1, "foo", 0, NO_FIN, &last_packet);  // Packet 1
   EXPECT_EQ(QuicPacketNumber(1u), last_packet);
   SendStreamDataToPeer(3, "foo", 0, NO_FIN, &last_packet);  // Packet 2
   EXPECT_EQ(QuicPacketNumber(2u), last_packet);
   SendAckPacketToPeer();                                    // Packet 3
   SendStreamDataToPeer(5, "foo", 0, NO_FIN, &last_packet);  // Packet 4
   EXPECT_EQ(QuicPacketNumber(4u), last_packet);
   SendStreamDataToPeer(1, "foo", 3, NO_FIN, &last_packet);  // Packet 5
   EXPECT_EQ(QuicPacketNumber(5u), last_packet);
   SendStreamDataToPeer(3, "foo", 3, NO_FIN, &last_packet);  // Packet 6
   EXPECT_EQ(QuicPacketNumber(6u), last_packet);

   // Client will ack packets 1, 2, [!3], 4, 5.
   EXPECT_CALL(*send_algorithm_, OnCongestionEvent(true, _, _, _, _));
   QuicAckFrame frame1 = ConstructAckFrame(5, 3);
   ProcessAckPacket(&frame1);

   // Now the client implicitly acks 3, and explicitly acks 6.
   EXPECT_CALL(*send_algorithm_, OnCongestionEvent(true, _, _, _, _));
   QuicAckFrame frame2 = InitAckFrame(6);
   ProcessAckPacket(&frame2);
 }

 TEST_P(QuicConnectionTest, DontLatchUnackedPacket) {
   if (connection_.SupportsMultiplePacketNumberSpaces()) {
     return;
   }
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
   EXPECT_CALL(visitor_, OnStreamFrame(_)).Times(1);
   ProcessDataPacket(1);
   QuicPacketCreatorPeer::SetPacketNumber(&peer_creator_, 2);
   SendStreamDataToPeer(1, "foo", 0, NO_FIN, nullptr);  // Packet 1;
   // From now on, we send acks, so the send algorithm won't mark them pending.
   SendAckPacketToPeer();  // Packet 2

   EXPECT_CALL(*send_algorithm_, OnCongestionEvent(true, _, _, _, _));
   QuicAckFrame frame = InitAckFrame(1);
   ProcessAckPacket(&frame);

   // Verify that our internal state has least-unacked as 2, because we're still
   // waiting for a potential ack for 2.

   EXPECT_EQ(QuicPacketNumber(2u), stop_waiting()->least_unacked);

   EXPECT_CALL(*send_algorithm_, OnCongestionEvent(true, _, _, _, _));
   frame = InitAckFrame(2);
   ProcessAckPacket(&frame);
   EXPECT_EQ(QuicPacketNumber(3u), stop_waiting()->least_unacked);

   // When we send an ack, we make sure our least-unacked makes sense.  In this
   // case since we're not waiting on an ack for 2 and all packets are acked, we
   // set it to 3.
   SendAckPacketToPeer();  // Packet 3
   // Least_unacked remains at 3 until another ack is received.
   EXPECT_EQ(QuicPacketNumber(3u), stop_waiting()->least_unacked);
   if (GetParam().no_stop_waiting) {
     // Expect no stop waiting frame is sent.
     EXPECT_FALSE(least_unacked().IsInitialized());
   } else {
     // Check that the outgoing ack had its packet number as least_unacked.
     EXPECT_EQ(QuicPacketNumber(3u), least_unacked());
   }

   // Ack the ack, which updates the rtt and raises the least unacked.
   EXPECT_CALL(*send_algorithm_, OnCongestionEvent(true, _, _, _, _));
   frame = InitAckFrame(3);
   ProcessAckPacket(&frame);

   SendStreamDataToPeer(1, "bar", 3, NO_FIN, nullptr);  // Packet 4
   EXPECT_EQ(QuicPacketNumber(4u), stop_waiting()->least_unacked);
   SendAckPacketToPeer();  // Packet 5
   if (GetParam().no_stop_waiting) {
     // Expect no stop waiting frame is sent.
     EXPECT_FALSE(least_unacked().IsInitialized());
   } else {
     EXPECT_EQ(QuicPacketNumber(4u), least_unacked());
   }

   // Send two data packets at the end, and ensure if the last one is acked,
   // the least unacked is raised above the ack packets.
   SendStreamDataToPeer(1, "bar", 6, NO_FIN, nullptr);  // Packet 6
   SendStreamDataToPeer(1, "bar", 9, NO_FIN, nullptr);  // Packet 7

   EXPECT_CALL(*send_algorithm_, OnCongestionEvent(true, _, _, _, _));
   frame = InitAckFrame({{QuicPacketNumber(1), QuicPacketNumber(5)},
                         {QuicPacketNumber(7), QuicPacketNumber(8)}});
   ProcessAckPacket(&frame);

   EXPECT_EQ(QuicPacketNumber(6u), stop_waiting()->least_unacked);
 }

 TEST_P(QuicConnectionTest, TLP) {
   connection_.SetMaxTailLossProbes(1);

   SendStreamDataToPeer(3, "foo", 0, NO_FIN, nullptr);
   EXPECT_EQ(QuicPacketNumber(1u), stop_waiting()->least_unacked);
   QuicTime retransmission_time =
       connection_.GetRetransmissionAlarm()->deadline();
   EXPECT_NE(QuicTime::Zero(), retransmission_time);

   EXPECT_EQ(QuicPacketNumber(1u), writer_->header().packet_number);
   // Simulate the retransmission alarm firing and sending a tlp,
   // so send algorithm's OnRetransmissionTimeout is not called.
   clock_.AdvanceTime(retransmission_time - clock_.Now());
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, QuicPacketNumber(2), _, _));
   connection_.GetRetransmissionAlarm()->Fire();
   EXPECT_EQ(QuicPacketNumber(2u), writer_->header().packet_number);
   // We do not raise the high water mark yet.
   EXPECT_EQ(QuicPacketNumber(1u), stop_waiting()->least_unacked);
 }

 TEST_P(QuicConnectionTest, TailLossProbeDelayForStreamDataInTLPR) {
   if (!connection_.session_decides_what_to_write() ||
       connection_.PtoEnabled()) {
     return;
   }

   // Set TLPR from QuicConfig.
   EXPECT_CALL(*send_algorithm_, SetFromConfig(_, _));
   QuicConfig config;
   QuicTagVector options;
   options.push_back(kTLPR);
   config.SetConnectionOptionsToSend(options);
   connection_.SetFromConfig(config);
   connection_.SetMaxTailLossProbes(1);

   SendStreamDataToPeer(3, "foo", 0, NO_FIN, nullptr);
   EXPECT_EQ(QuicPacketNumber(1u), stop_waiting()->least_unacked);

   QuicTime retransmission_time =
       connection_.GetRetransmissionAlarm()->deadline();
   EXPECT_NE(QuicTime::Zero(), retransmission_time);
   QuicTime::Delta expected_tlp_delay =
       0.5 * manager_->GetRttStats()->SmoothedOrInitialRtt();
   EXPECT_EQ(expected_tlp_delay, retransmission_time - clock_.Now());

   EXPECT_EQ(QuicPacketNumber(1u), writer_->header().packet_number);
   // Simulate firing of the retransmission alarm and retransmit the packet.
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, QuicPacketNumber(2), _, _));
   clock_.AdvanceTime(retransmission_time - clock_.Now());
   connection_.GetRetransmissionAlarm()->Fire();
   EXPECT_EQ(QuicPacketNumber(2u), writer_->header().packet_number);

   // We do not raise the high water mark yet.
   EXPECT_EQ(QuicPacketNumber(1u), stop_waiting()->least_unacked);
 }

 TEST_P(QuicConnectionTest, TailLossProbeDelayForNonStreamDataInTLPR) {
   if (!connection_.session_decides_what_to_write() ||
       connection_.PtoEnabled()) {
     return;
   }

   // Set TLPR from QuicConfig.
   EXPECT_CALL(*send_algorithm_, SetFromConfig(_, _));
   QuicConfig config;
   QuicTagVector options;
   options.push_back(kTLPR);
   config.SetConnectionOptionsToSend(options);
   connection_.SetFromConfig(config);
   connection_.SetMaxTailLossProbes(1);

   // Sets retransmittable on wire.
   const QuicTime::Delta retransmittable_on_wire_timeout =
       QuicTime::Delta::FromMilliseconds(50);
   connection_.set_retransmittable_on_wire_timeout(
       retransmittable_on_wire_timeout);

   EXPECT_TRUE(connection_.connected());
   EXPECT_CALL(visitor_, ShouldKeepConnectionAlive())
       .WillRepeatedly(Return(true));
   EXPECT_FALSE(connection_.GetPathDegradingAlarm()->IsSet());
   EXPECT_FALSE(connection_.IsPathDegrading());
   EXPECT_FALSE(connection_.GetPingAlarm()->IsSet());

   const char data[] = "data";
   size_t data_size = strlen(data);
   QuicStreamOffset offset = 0;

   // Send a data packet.
   connection_.SendStreamDataWithString(1, data, offset, NO_FIN);
   offset += data_size;

   // Path degrading alarm should be set when there is a retransmittable packet
   // on the wire.
   EXPECT_TRUE(connection_.GetPathDegradingAlarm()->IsSet());

   // Verify the path degrading delay.
   // First TLP with stream data.
   QuicTime::Delta srtt = manager_->GetRttStats()->SmoothedOrInitialRtt();
   QuicTime::Delta expected_delay = 0.5 * srtt;
   // Add 1st RTO.
   QuicTime::Delta retransmission_delay =
       QuicTime::Delta::FromMilliseconds(kDefaultRetransmissionTimeMs);
   expected_delay = expected_delay + retransmission_delay;
   // Add 2nd RTO.
   expected_delay = expected_delay + retransmission_delay * 2;
   EXPECT_EQ(expected_delay,
             QuicConnectionPeer::GetSentPacketManager(&connection_)
                 ->GetPathDegradingDelay());
   ASSERT_TRUE(connection_.sent_packet_manager().HasInFlightPackets());

   // The ping alarm is set for the ping timeout, not the shorter
   // retransmittable_on_wire_timeout.
   EXPECT_TRUE(connection_.GetPingAlarm()->IsSet());
   EXPECT_EQ(connection_.ping_timeout(),
             connection_.GetPingAlarm()->deadline() - clock_.ApproximateNow());

   // Receive an ACK for the data packet.
   clock_.AdvanceTime(QuicTime::Delta::FromMilliseconds(5));
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
   EXPECT_CALL(*send_algorithm_, OnCongestionEvent(true, _, _, _, _));
   QuicAckFrame frame =
       InitAckFrame({{QuicPacketNumber(1), QuicPacketNumber(2)}});
   ProcessAckPacket(&frame);

   // Path degrading alarm should be cancelled as there is no more
   // reretransmittable packets on the wire.
   EXPECT_FALSE(connection_.GetPathDegradingAlarm()->IsSet());
   // The ping alarm should be set to the retransmittable_on_wire_timeout.
   EXPECT_TRUE(connection_.GetPingAlarm()->IsSet());
   EXPECT_EQ(retransmittable_on_wire_timeout,
             connection_.GetPingAlarm()->deadline() - clock_.ApproximateNow());

   // Simulate firing of the retransmittable on wire and send a PING.
   EXPECT_CALL(visitor_, SendPing()).WillOnce(Invoke([this]() { SendPing(); }));
   clock_.AdvanceTime(retransmittable_on_wire_timeout);
   connection_.GetPingAlarm()->Fire();

   // The retransmission alarm and the path degrading alarm should be set as
   // there is a retransmittable packet (PING) on the wire,
   EXPECT_TRUE(connection_.GetRetransmissionAlarm()->IsSet());
   EXPECT_TRUE(connection_.GetPathDegradingAlarm()->IsSet());

   // Verify the retransmission delay.
   QuicTime::Delta min_rto_timeout =
       QuicTime::Delta::FromMilliseconds(kMinRetransmissionTimeMs);
   srtt = manager_->GetRttStats()->SmoothedOrInitialRtt();

   // First TLP without unacked stream data will no longer use TLPR.
   expected_delay = std::max(2 * srtt, 1.5 * srtt + 0.5 * min_rto_timeout);
   EXPECT_EQ(expected_delay,
             connection_.GetRetransmissionAlarm()->deadline() - clock_.Now());

   // Verify the path degrading delay = TLP delay + 1st RTO + 2nd RTO.
   // Add 1st RTO.
   retransmission_delay =
       std::max(manager_->GetRttStats()->smoothed_rtt() +
                    4 * manager_->GetRttStats()->mean_deviation(),
                min_rto_timeout);
   expected_delay = expected_delay + retransmission_delay;
   // Add 2nd RTO.
   expected_delay = expected_delay + retransmission_delay * 2;
   EXPECT_EQ(expected_delay,
             QuicConnectionPeer::GetSentPacketManager(&connection_)
                 ->GetPathDegradingDelay());

   // The ping alarm is set for the ping timeout, not the shorter
   // retransmittable_on_wire_timeout.
   EXPECT_TRUE(connection_.GetPingAlarm()->IsSet());
   EXPECT_EQ(connection_.ping_timeout(),
             connection_.GetPingAlarm()->deadline() - clock_.ApproximateNow());

   // Advance a small period of time: 5ms. And receive a retransmitted ACK.
   // This will update the retransmission alarm, verify the retransmission delay
   // is correct.
   clock_.AdvanceTime(QuicTime::Delta::FromMilliseconds(5));
   QuicAckFrame ack = InitAckFrame({{QuicPacketNumber(1), QuicPacketNumber(2)}});
   ProcessAckPacket(&ack);

   // Verify the retransmission delay.
   // First TLP without unacked stream data will no longer use TLPR.
   expected_delay = std::max(2 * srtt, 1.5 * srtt + 0.5 * min_rto_timeout);
   expected_delay = expected_delay - QuicTime::Delta::FromMilliseconds(5);
   EXPECT_EQ(expected_delay,
             connection_.GetRetransmissionAlarm()->deadline() - clock_.Now());
 }

 TEST_P(QuicConnectionTest, RTO) {
   if (connection_.PtoEnabled()) {
     return;
   }
   connection_.SetMaxTailLossProbes(0);

   QuicTime default_retransmission_time =
       clock_.ApproximateNow() + DefaultRetransmissionTime();
   SendStreamDataToPeer(3, "foo", 0, NO_FIN, nullptr);
   EXPECT_EQ(QuicPacketNumber(1u), stop_waiting()->least_unacked);

   EXPECT_EQ(QuicPacketNumber(1u), writer_->header().packet_number);
   EXPECT_EQ(default_retransmission_time,
             connection_.GetRetransmissionAlarm()->deadline());
   // Simulate the retransmission alarm firing.
   clock_.AdvanceTime(DefaultRetransmissionTime());
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, QuicPacketNumber(2), _, _));
   connection_.GetRetransmissionAlarm()->Fire();
   EXPECT_EQ(QuicPacketNumber(2u), writer_->header().packet_number);
   // We do not raise the high water mark yet.
   EXPECT_EQ(QuicPacketNumber(1u), stop_waiting()->least_unacked);
 }

 // Regression test of b/133771183.
 TEST_P(QuicConnectionTest, RtoWithNoDataToRetransmit) {
   if (!connection_.session_decides_what_to_write() ||
       connection_.PtoEnabled()) {
     return;
   }
   connection_.SetDefaultEncryptionLevel(ENCRYPTION_FORWARD_SECURE);
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
   connection_.SetMaxTailLossProbes(0);

   SendStreamDataToPeer(3, "foo", 0, NO_FIN, nullptr);
   // Connection is cwnd limited.
   CongestionBlockWrites();
   // Stream gets reset.
   SendRstStream(3, QUIC_ERROR_PROCESSING_STREAM, 3);
   // Simulate the retransmission alarm firing.
   clock_.AdvanceTime(DefaultRetransmissionTime());
   // RTO fires, but there is no packet to be RTOed.
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(1);
   connection_.GetRetransmissionAlarm()->Fire();
   EXPECT_EQ(1u, writer_->rst_stream_frames().size());

   EXPECT_CALL(visitor_, OnStreamFrame(_)).Times(40);
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(20);
   EXPECT_CALL(visitor_, WillingAndAbleToWrite()).WillRepeatedly(Return(false));
   EXPECT_CALL(visitor_, OnAckNeedsRetransmittableFrame()).Times(1);
   // Receives packets 1 - 40.
   for (size_t i = 1; i <= 40; ++i) {
     ProcessDataPacket(i);
   }
 }

 TEST_P(QuicConnectionTest, RetransmitWithSameEncryptionLevel) {
   use_tagging_decrypter();

   // A TaggingEncrypter puts kTagSize copies of the given byte (0x01 here) at
   // the end of the packet. We can test this to check which encrypter was used.
   connection_.SetEncrypter(ENCRYPTION_INITIAL,
                            std::make_unique<TaggingEncrypter>(0x01));
   QuicByteCount packet_size;
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _))
       .WillOnce(SaveArg<3>(&packet_size));
   connection_.SendCryptoDataWithString("foo", 0);
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(AnyNumber());
   EXPECT_EQ(0x01010101u, writer_->final_bytes_of_last_packet());

   connection_.SetEncrypter(ENCRYPTION_ZERO_RTT,
                            std::make_unique<TaggingEncrypter>(0x02));
   connection_.SetDefaultEncryptionLevel(ENCRYPTION_ZERO_RTT);
   SendStreamDataToPeer(3, "foo", 0, NO_FIN, nullptr);
   EXPECT_EQ(0x02020202u, writer_->final_bytes_of_last_packet());

   {
     InSequence s;
     EXPECT_CALL(*send_algorithm_,
                 OnPacketSent(_, _, QuicPacketNumber(3), _, _));
     EXPECT_CALL(*send_algorithm_,
                 OnPacketSent(_, _, QuicPacketNumber(4), _, _));
   }

   // Manually mark both packets for retransmission.
   connection_.RetransmitUnackedPackets(ALL_UNACKED_RETRANSMISSION);

   // Packet should have been sent with ENCRYPTION_INITIAL.
   EXPECT_EQ(0x01010101u, writer_->final_bytes_of_previous_packet());

   // Packet should have been sent with ENCRYPTION_ZERO_RTT.
   EXPECT_EQ(0x02020202u, writer_->final_bytes_of_last_packet());
 }

 TEST_P(QuicConnectionTest, SendHandshakeMessages) {
   use_tagging_decrypter();
   // A TaggingEncrypter puts kTagSize copies of the given byte (0x01 here) at
   // the end of the packet. We can test this to check which encrypter was used.
   connection_.SetEncrypter(ENCRYPTION_INITIAL,
                            std::make_unique<TaggingEncrypter>(0x01));

   // Attempt to send a handshake message and have the socket block.
   EXPECT_CALL(*send_algorithm_, CanSend(_)).WillRepeatedly(Return(true));
   BlockOnNextWrite();
   connection_.SendCryptoDataWithString("foo", 0);
   // The packet should be serialized, but not queued.
   EXPECT_EQ(1u, connection_.NumQueuedPackets());

   // Switch to the new encrypter.
   connection_.SetEncrypter(ENCRYPTION_ZERO_RTT,
                            std::make_unique<TaggingEncrypter>(0x02));
   connection_.SetDefaultEncryptionLevel(ENCRYPTION_ZERO_RTT);

   // Now become writeable and flush the packets.
   writer_->SetWritable();
   EXPECT_CALL(visitor_, OnCanWrite());
   connection_.OnCanWrite();
   EXPECT_EQ(0u, connection_.NumQueuedPackets());

   // Verify that the handshake packet went out at the null encryption.
   EXPECT_EQ(0x01010101u, writer_->final_bytes_of_last_packet());
 }

 TEST_P(QuicConnectionTest,
        DropRetransmitsForNullEncryptedPacketAfterForwardSecure) {
   use_tagging_decrypter();
   connection_.SetEncrypter(ENCRYPTION_INITIAL,
                            std::make_unique<TaggingEncrypter>(0x01));
   QuicPacketNumber packet_number;
   connection_.SendCryptoStreamData();

   // Simulate the retransmission alarm firing and the socket blocking.
   BlockOnNextWrite();
   clock_.AdvanceTime(DefaultRetransmissionTime());
   if (GetQuicReloadableFlag(quic_treat_queued_packets_as_sent)) {
     EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(1);
   } else {
     EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(0);
   }
   connection_.GetRetransmissionAlarm()->Fire();
   EXPECT_EQ(1u, connection_.NumQueuedPackets());

   // Go forward secure.
   connection_.SetEncrypter(ENCRYPTION_FORWARD_SECURE,
                            std::make_unique<TaggingEncrypter>(0x02));
   connection_.SetDefaultEncryptionLevel(ENCRYPTION_FORWARD_SECURE);
   notifier_.NeuterUnencryptedData();
   connection_.NeuterUnencryptedPackets();
   connection_.OnHandshakeComplete();

   EXPECT_EQ(QuicTime::Zero(), connection_.GetRetransmissionAlarm()->deadline());
   // Unblock the socket and ensure that no packets are sent.
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(0);
   writer_->SetWritable();
   connection_.OnCanWrite();
 }

 TEST_P(QuicConnectionTest, RetransmitPacketsWithInitialEncryption) {
   use_tagging_decrypter();
   connection_.SetEncrypter(ENCRYPTION_INITIAL,
                            std::make_unique<TaggingEncrypter>(0x01));
   connection_.SetDefaultEncryptionLevel(ENCRYPTION_INITIAL);

   connection_.SendCryptoDataWithString("foo", 0);

   connection_.SetEncrypter(ENCRYPTION_ZERO_RTT,
                            std::make_unique<TaggingEncrypter>(0x02));
   connection_.SetDefaultEncryptionLevel(ENCRYPTION_ZERO_RTT);

   SendStreamDataToPeer(2, "bar", 0, NO_FIN, nullptr);
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(1);

   connection_.RetransmitUnackedPackets(ALL_INITIAL_RETRANSMISSION);
 }

 TEST_P(QuicConnectionTest, BufferNonDecryptablePackets) {
   if (connection_.SupportsMultiplePacketNumberSpaces()) {
     return;
   }
   // SetFromConfig is always called after construction from InitializeSession.
   EXPECT_CALL(*send_algorithm_, SetFromConfig(_, _));
   QuicConfig config;
   connection_.SetFromConfig(config);
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
   use_tagging_decrypter();

   const uint8_t tag = 0x07;
   peer_framer_.SetEncrypter(ENCRYPTION_ZERO_RTT,
                             std::make_unique<TaggingEncrypter>(tag));

   // Process an encrypted packet which can not yet be decrypted which should
   // result in the packet being buffered.
   ProcessDataPacketAtLevel(1, !kHasStopWaiting, ENCRYPTION_ZERO_RTT);

   // Transition to the new encryption state and process another encrypted packet
   // which should result in the original packet being processed.
   SetDecrypter(ENCRYPTION_ZERO_RTT,
                std::make_unique<StrictTaggingDecrypter>(tag));
   connection_.SetDefaultEncryptionLevel(ENCRYPTION_ZERO_RTT);
   connection_.SetEncrypter(ENCRYPTION_ZERO_RTT,
                            std::make_unique<TaggingEncrypter>(tag));
   EXPECT_CALL(visitor_, OnStreamFrame(_)).Times(2);
   ProcessDataPacketAtLevel(2, !kHasStopWaiting, ENCRYPTION_ZERO_RTT);

   // Finally, process a third packet and note that we do not reprocess the
   // buffered packet.
   EXPECT_CALL(visitor_, OnStreamFrame(_)).Times(1);
   ProcessDataPacketAtLevel(3, !kHasStopWaiting, ENCRYPTION_ZERO_RTT);
 }

 TEST_P(QuicConnectionTest, TestRetransmitOrder) {
   if (connection_.PtoEnabled()) {
     return;
   }
   connection_.SetMaxTailLossProbes(0);

   QuicByteCount first_packet_size;
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _))
       .WillOnce(SaveArg<3>(&first_packet_size));

   connection_.SendStreamDataWithString(3, "first_packet", 0, NO_FIN);
   QuicByteCount second_packet_size;
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _))
       .WillOnce(SaveArg<3>(&second_packet_size));
   connection_.SendStreamDataWithString(3, "second_packet", 12, NO_FIN);
   EXPECT_NE(first_packet_size, second_packet_size);
   // Advance the clock by huge time to make sure packets will be retransmitted.
   clock_.AdvanceTime(QuicTime::Delta::FromSeconds(10));
   {
     InSequence s;
     EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, first_packet_size, _));
     EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, second_packet_size, _));
   }
   connection_.GetRetransmissionAlarm()->Fire();

   // Advance again and expect the packets to be sent again in the same order.
   clock_.AdvanceTime(QuicTime::Delta::FromSeconds(20));
   {
     InSequence s;
     EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, first_packet_size, _));
     EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, second_packet_size, _));
   }
   connection_.GetRetransmissionAlarm()->Fire();
 }

 TEST_P(QuicConnectionTest, Buffer100NonDecryptablePacketsThenKeyChange) {
   if (connection_.SupportsMultiplePacketNumberSpaces()) {
     return;
   }
   // SetFromConfig is always called after construction from InitializeSession.
   EXPECT_CALL(*send_algorithm_, SetFromConfig(_, _));
   QuicConfig config;
   config.set_max_undecryptable_packets(100);
   connection_.SetFromConfig(config);
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
   use_tagging_decrypter();

   const uint8_t tag = 0x07;
   peer_framer_.SetEncrypter(ENCRYPTION_ZERO_RTT,
                             std::make_unique<TaggingEncrypter>(tag));

   // Process an encrypted packet which can not yet be decrypted which should
   // result in the packet being buffered.
   for (uint64_t i = 1; i <= 100; ++i) {
     ProcessDataPacketAtLevel(i, !kHasStopWaiting, ENCRYPTION_ZERO_RTT);
   }

   // Transition to the new encryption state and process another encrypted packet
   // which should result in the original packets being processed.
   EXPECT_FALSE(connection_.GetProcessUndecryptablePacketsAlarm()->IsSet());
   SetDecrypter(ENCRYPTION_ZERO_RTT,
                std::make_unique<StrictTaggingDecrypter>(tag));
   EXPECT_TRUE(connection_.GetProcessUndecryptablePacketsAlarm()->IsSet());
   connection_.SetDefaultEncryptionLevel(ENCRYPTION_ZERO_RTT);
   connection_.SetEncrypter(ENCRYPTION_ZERO_RTT,
                            std::make_unique<TaggingEncrypter>(tag));

   EXPECT_CALL(visitor_, OnStreamFrame(_)).Times(100);
   connection_.GetProcessUndecryptablePacketsAlarm()->Fire();

   // Finally, process a third packet and note that we do not reprocess the
   // buffered packet.
   EXPECT_CALL(visitor_, OnStreamFrame(_)).Times(1);
   ProcessDataPacketAtLevel(102, !kHasStopWaiting, ENCRYPTION_ZERO_RTT);
 }

 TEST_P(QuicConnectionTest, SetRTOAfterWritingToSocket) {
   BlockOnNextWrite();
   if (GetQuicReloadableFlag(quic_treat_queued_packets_as_sent)) {
     EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(1);
   } else {
     EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(0);
   }
   connection_.SendStreamDataWithString(1, "foo", 0, NO_FIN);
   if (GetQuicReloadableFlag(quic_treat_queued_packets_as_sent)) {
     EXPECT_TRUE(connection_.GetRetransmissionAlarm()->IsSet());
   } else {
     // Make sure that RTO is not started when the packet is queued.
     EXPECT_FALSE(connection_.GetRetransmissionAlarm()->IsSet());
   }

   // Test that RTO is started once we write to the socket.
   writer_->SetWritable();
   if (GetQuicReloadableFlag(quic_treat_queued_packets_as_sent)) {
     EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(0);
   } else {
     EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(1);
   }
   connection_.OnCanWrite();
   EXPECT_TRUE(connection_.GetRetransmissionAlarm()->IsSet());
 }

 TEST_P(QuicConnectionTest, DelayRTOWithAckReceipt) {
   if (connection_.PtoEnabled()) {
     return;
   }
   connection_.SetMaxTailLossProbes(0);

   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(2);
   connection_.SendStreamDataWithString(2, "foo", 0, NO_FIN);
   connection_.SendStreamDataWithString(3, "bar", 0, NO_FIN);
   QuicAlarm* retransmission_alarm = connection_.GetRetransmissionAlarm();
   EXPECT_TRUE(retransmission_alarm->IsSet());
   EXPECT_EQ(DefaultRetransmissionTime(),
             retransmission_alarm->deadline() - clock_.Now());

   // Advance the time right before the RTO, then receive an ack for the first
   // packet to delay the RTO.
   clock_.AdvanceTime(DefaultRetransmissionTime());
   EXPECT_CALL(*send_algorithm_, OnCongestionEvent(true, _, _, _, _));
   QuicAckFrame ack = InitAckFrame(1);
   ProcessAckPacket(&ack);
   // Now we have an RTT sample of DefaultRetransmissionTime(500ms),
   // so the RTO has increased to 2 * SRTT.
   EXPECT_TRUE(retransmission_alarm->IsSet());
   EXPECT_EQ(retransmission_alarm->deadline() - clock_.Now(),
             2 * DefaultRetransmissionTime());

   // Move forward past the original RTO and ensure the RTO is still pending.
   clock_.AdvanceTime(2 * DefaultRetransmissionTime());

   // Ensure the second packet gets retransmitted when it finally fires.
   EXPECT_TRUE(retransmission_alarm->IsSet());
   EXPECT_EQ(retransmission_alarm->deadline(), clock_.ApproximateNow());
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _));
   // Manually cancel the alarm to simulate a real test.
   connection_.GetRetransmissionAlarm()->Fire();

   // The new retransmitted packet number should set the RTO to a larger value
   // than previously.
   EXPECT_TRUE(retransmission_alarm->IsSet());
   QuicTime next_rto_time = retransmission_alarm->deadline();
   QuicTime expected_rto_time =
       connection_.sent_packet_manager().GetRetransmissionTime();
   EXPECT_EQ(next_rto_time, expected_rto_time);
 }

 TEST_P(QuicConnectionTest, TestQueued) {
   connection_.SetMaxTailLossProbes(0);

   EXPECT_EQ(0u, connection_.NumQueuedPackets());
   BlockOnNextWrite();
   connection_.SendStreamDataWithString(1, "foo", 0, NO_FIN);
   EXPECT_EQ(1u, connection_.NumQueuedPackets());

   // Unblock the writes and actually send.
   writer_->SetWritable();
   connection_.OnCanWrite();
   EXPECT_EQ(0u, connection_.NumQueuedPackets());
 }

 TEST_P(QuicConnectionTest, InitialTimeout) {
   EXPECT_TRUE(connection_.connected());
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(AnyNumber());
   EXPECT_FALSE(connection_.GetTimeoutAlarm()->IsSet());

   // SetFromConfig sets the initial timeouts before negotiation.
   EXPECT_CALL(*send_algorithm_, SetFromConfig(_, _));
   QuicConfig config;
   connection_.SetFromConfig(config);
   // Subtract a second from the idle timeout on the client side.
   QuicTime default_timeout =
       clock_.ApproximateNow() +
       QuicTime::Delta::FromSeconds(kInitialIdleTimeoutSecs - 1);
   EXPECT_EQ(default_timeout, connection_.GetTimeoutAlarm()->deadline());

   EXPECT_CALL(visitor_,
               OnConnectionClosed(_, ConnectionCloseSource::FROM_SELF));
   // Simulate the timeout alarm firing.
   clock_.AdvanceTime(QuicTime::Delta::FromSeconds(kInitialIdleTimeoutSecs - 1));
   connection_.GetTimeoutAlarm()->Fire();

   EXPECT_FALSE(connection_.GetTimeoutAlarm()->IsSet());
   EXPECT_FALSE(connection_.connected());

   EXPECT_FALSE(connection_.GetAckAlarm()->IsSet());
   EXPECT_FALSE(connection_.GetPingAlarm()->IsSet());
   EXPECT_FALSE(connection_.GetRetransmissionAlarm()->IsSet());
   EXPECT_FALSE(connection_.GetSendAlarm()->IsSet());
   EXPECT_FALSE(connection_.GetMtuDiscoveryAlarm()->IsSet());
   EXPECT_FALSE(connection_.GetProcessUndecryptablePacketsAlarm()->IsSet());
   TestConnectionCloseQuicErrorCode(QUIC_NETWORK_IDLE_TIMEOUT);
 }

 TEST_P(QuicConnectionTest, IdleTimeoutAfterFirstSentPacket) {
   EXPECT_TRUE(connection_.connected());
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(AnyNumber());
   EXPECT_FALSE(connection_.GetTimeoutAlarm()->IsSet());

   EXPECT_CALL(*send_algorithm_, SetFromConfig(_, _));
   QuicConfig config;
   connection_.SetFromConfig(config);
   EXPECT_TRUE(connection_.GetTimeoutAlarm()->IsSet());
   QuicTime initial_ddl =
       clock_.ApproximateNow() +
       QuicTime::Delta::FromSeconds(kInitialIdleTimeoutSecs - 1);
   EXPECT_EQ(initial_ddl, connection_.GetTimeoutAlarm()->deadline());
   EXPECT_TRUE(connection_.connected());

   // Advance the time and send the first packet to the peer.
   clock_.AdvanceTime(QuicTime::Delta::FromMicroseconds(20));
   QuicPacketNumber last_packet;
   SendStreamDataToPeer(1, "foo", 0, NO_FIN, &last_packet);
   EXPECT_EQ(QuicPacketNumber(1u), last_packet);
   // This will be the updated deadline for the connection to idle time out.
   QuicTime new_ddl = clock_.ApproximateNow() +
                      QuicTime::Delta::FromSeconds(kInitialIdleTimeoutSecs - 1);

   // Simulate the timeout alarm firing, the connection should not be closed as
   // a new packet has been sent.
   EXPECT_CALL(visitor_, OnConnectionClosed(_, _)).Times(0);
   QuicTime::Delta delay = initial_ddl - clock_.ApproximateNow();
   clock_.AdvanceTime(delay);
   connection_.GetTimeoutAlarm()->Fire();
   // Verify the timeout alarm deadline is updated.
   EXPECT_TRUE(connection_.connected());
   EXPECT_TRUE(connection_.GetTimeoutAlarm()->IsSet());
   EXPECT_EQ(new_ddl, connection_.GetTimeoutAlarm()->deadline());

   // Simulate the timeout alarm firing again, the connection now should be
   // closed.
   EXPECT_CALL(visitor_,
               OnConnectionClosed(_, ConnectionCloseSource::FROM_SELF));
   clock_.AdvanceTime(new_ddl - clock_.ApproximateNow());
   connection_.GetTimeoutAlarm()->Fire();
   EXPECT_FALSE(connection_.GetTimeoutAlarm()->IsSet());
   EXPECT_FALSE(connection_.connected());

   EXPECT_FALSE(connection_.GetAckAlarm()->IsSet());
   EXPECT_FALSE(connection_.GetPingAlarm()->IsSet());
   EXPECT_FALSE(connection_.GetRetransmissionAlarm()->IsSet());
   EXPECT_FALSE(connection_.GetSendAlarm()->IsSet());
   EXPECT_FALSE(connection_.GetMtuDiscoveryAlarm()->IsSet());
   TestConnectionCloseQuicErrorCode(QUIC_NETWORK_IDLE_TIMEOUT);
 }

 TEST_P(QuicConnectionTest, IdleTimeoutAfterSendTwoPackets) {
   EXPECT_TRUE(connection_.connected());
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(AnyNumber());
   EXPECT_FALSE(connection_.GetTimeoutAlarm()->IsSet());

   EXPECT_CALL(*send_algorithm_, SetFromConfig(_, _));
   QuicConfig config;
   connection_.SetFromConfig(config);
   EXPECT_TRUE(connection_.GetTimeoutAlarm()->IsSet());
   QuicTime initial_ddl =
       clock_.ApproximateNow() +
       QuicTime::Delta::FromSeconds(kInitialIdleTimeoutSecs - 1);
   EXPECT_EQ(initial_ddl, connection_.GetTimeoutAlarm()->deadline());
   EXPECT_TRUE(connection_.connected());

   // Immediately send the first packet, this is a rare case but test code will
   // hit this issue often as MockClock used for tests doesn't move with code
   // execution until manually adjusted.
   QuicPacketNumber last_packet;
   SendStreamDataToPeer(1, "foo", 0, NO_FIN, &last_packet);
   EXPECT_EQ(QuicPacketNumber(1u), last_packet);

   // Advance the time and send the second packet to the peer.
   clock_.AdvanceTime(QuicTime::Delta::FromMilliseconds(20));
   SendStreamDataToPeer(1, "foo", 0, NO_FIN, &last_packet);
   EXPECT_EQ(QuicPacketNumber(2u), last_packet);

   // Simulate the timeout alarm firing, the connection will be closed.
   EXPECT_CALL(visitor_,
               OnConnectionClosed(_, ConnectionCloseSource::FROM_SELF));
   clock_.AdvanceTime(initial_ddl - clock_.ApproximateNow());
   connection_.GetTimeoutAlarm()->Fire();

   EXPECT_FALSE(connection_.GetTimeoutAlarm()->IsSet());
   EXPECT_FALSE(connection_.connected());

   EXPECT_FALSE(connection_.GetAckAlarm()->IsSet());
   EXPECT_FALSE(connection_.GetPingAlarm()->IsSet());
   EXPECT_FALSE(connection_.GetRetransmissionAlarm()->IsSet());
   EXPECT_FALSE(connection_.GetSendAlarm()->IsSet());
   EXPECT_FALSE(connection_.GetMtuDiscoveryAlarm()->IsSet());
   TestConnectionCloseQuicErrorCode(QUIC_NETWORK_IDLE_TIMEOUT);
 }

 TEST_P(QuicConnectionTest, HandshakeTimeout) {
   // Use a shorter handshake timeout than idle timeout for this test.
   const QuicTime::Delta timeout = QuicTime::Delta::FromSeconds(5);
   connection_.SetNetworkTimeouts(timeout, timeout);
   EXPECT_TRUE(connection_.connected());
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(AnyNumber());

   QuicTime handshake_timeout =
       clock_.ApproximateNow() + timeout - QuicTime::Delta::FromSeconds(1);
   EXPECT_EQ(handshake_timeout, connection_.GetTimeoutAlarm()->deadline());
   EXPECT_TRUE(connection_.connected());

   // Send and ack new data 3 seconds later to lengthen the idle timeout.
   SendStreamDataToPeer(
       GetNthClientInitiatedStreamId(0, connection_.transport_version()),
       "GET /", 0, FIN, nullptr);
   clock_.AdvanceTime(QuicTime::Delta::FromSeconds(3));
   QuicAckFrame frame = InitAckFrame(1);
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
   EXPECT_CALL(*send_algorithm_, OnCongestionEvent(true, _, _, _, _));
   ProcessAckPacket(&frame);

   // Fire early to verify it wouldn't timeout yet.
   connection_.GetTimeoutAlarm()->Fire();
   EXPECT_TRUE(connection_.GetTimeoutAlarm()->IsSet());
   EXPECT_TRUE(connection_.connected());

   clock_.AdvanceTime(timeout - QuicTime::Delta::FromSeconds(2));

   EXPECT_CALL(visitor_,
               OnConnectionClosed(_, ConnectionCloseSource::FROM_SELF));
   // Simulate the timeout alarm firing.
   connection_.GetTimeoutAlarm()->Fire();

   EXPECT_FALSE(connection_.GetTimeoutAlarm()->IsSet());
   EXPECT_FALSE(connection_.connected());

   EXPECT_FALSE(connection_.GetAckAlarm()->IsSet());
   EXPECT_FALSE(connection_.GetPingAlarm()->IsSet());
   EXPECT_FALSE(connection_.GetRetransmissionAlarm()->IsSet());
   EXPECT_FALSE(connection_.GetSendAlarm()->IsSet());
   TestConnectionCloseQuicErrorCode(QUIC_HANDSHAKE_TIMEOUT);
 }

 TEST_P(QuicConnectionTest, PingAfterSend) {
   if (connection_.SupportsMultiplePacketNumberSpaces()) {
     return;
   }
   EXPECT_TRUE(connection_.connected());
   EXPECT_CALL(visitor_, ShouldKeepConnectionAlive())
       .WillRepeatedly(Return(true));
   EXPECT_FALSE(connection_.GetPingAlarm()->IsSet());

   // Advance to 5ms, and send a packet to the peer, which will set
   // the ping alarm.
   clock_.AdvanceTime(QuicTime::Delta::FromMilliseconds(5));
   EXPECT_FALSE(connection_.GetRetransmissionAlarm()->IsSet());
   SendStreamDataToPeer(
       GetNthClientInitiatedStreamId(0, connection_.transport_version()),
       "GET /", 0, FIN, nullptr);
   EXPECT_TRUE(connection_.GetPingAlarm()->IsSet());
   EXPECT_EQ(QuicTime::Delta::FromSeconds(15),
             connection_.GetPingAlarm()->deadline() - clock_.ApproximateNow());

   // Now recevie an ACK of the previous packet, which will move the
   // ping alarm forward.
   clock_.AdvanceTime(QuicTime::Delta::FromMilliseconds(5));
   QuicAckFrame frame = InitAckFrame(1);
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
   EXPECT_CALL(*send_algorithm_, OnCongestionEvent(true, _, _, _, _));
   ProcessAckPacket(&frame);
   EXPECT_TRUE(connection_.GetPingAlarm()->IsSet());
   // The ping timer is set slightly less than 15 seconds in the future, because
   // of the 1s ping timer alarm granularity.
   EXPECT_EQ(
       QuicTime::Delta::FromSeconds(15) - QuicTime::Delta::FromMilliseconds(5),
       connection_.GetPingAlarm()->deadline() - clock_.ApproximateNow());

   writer_->Reset();
   clock_.AdvanceTime(QuicTime::Delta::FromSeconds(15));
   EXPECT_CALL(visitor_, SendPing()).WillOnce(Invoke([this]() { SendPing(); }));
   connection_.GetPingAlarm()->Fire();
   size_t padding_frame_count = writer_->padding_frames().size();
   EXPECT_EQ(padding_frame_count + 1u, writer_->frame_count());
   ASSERT_EQ(1u, writer_->ping_frames().size());
   writer_->Reset();

   EXPECT_CALL(visitor_, ShouldKeepConnectionAlive())
       .WillRepeatedly(Return(false));
   clock_.AdvanceTime(QuicTime::Delta::FromMilliseconds(5));
   SendAckPacketToPeer();

   EXPECT_FALSE(connection_.GetPingAlarm()->IsSet());
 }

 TEST_P(QuicConnectionTest, ReducedPingTimeout) {
   if (connection_.SupportsMultiplePacketNumberSpaces()) {
     return;
   }
   EXPECT_TRUE(connection_.connected());
   EXPECT_CALL(visitor_, ShouldKeepConnectionAlive())
       .WillRepeatedly(Return(true));
   EXPECT_FALSE(connection_.GetPingAlarm()->IsSet());

   // Use a reduced ping timeout for this connection.
   connection_.set_ping_timeout(QuicTime::Delta::FromSeconds(10));

   // Advance to 5ms, and send a packet to the peer, which will set
   // the ping alarm.
   clock_.AdvanceTime(QuicTime::Delta::FromMilliseconds(5));
   EXPECT_FALSE(connection_.GetRetransmissionAlarm()->IsSet());
   SendStreamDataToPeer(
       GetNthClientInitiatedStreamId(0, connection_.transport_version()),
       "GET /", 0, FIN, nullptr);
   EXPECT_TRUE(connection_.GetPingAlarm()->IsSet());
   EXPECT_EQ(QuicTime::Delta::FromSeconds(10),
             connection_.GetPingAlarm()->deadline() - clock_.ApproximateNow());

   // Now recevie an ACK of the previous packet, which will move the
   // ping alarm forward.
   clock_.AdvanceTime(QuicTime::Delta::FromMilliseconds(5));
   QuicAckFrame frame = InitAckFrame(1);
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
   EXPECT_CALL(*send_algorithm_, OnCongestionEvent(true, _, _, _, _));
   ProcessAckPacket(&frame);
   EXPECT_TRUE(connection_.GetPingAlarm()->IsSet());
   // The ping timer is set slightly less than 10 seconds in the future, because
   // of the 1s ping timer alarm granularity.
   EXPECT_EQ(
       QuicTime::Delta::FromSeconds(10) - QuicTime::Delta::FromMilliseconds(5),
       connection_.GetPingAlarm()->deadline() - clock_.ApproximateNow());

   writer_->Reset();
   clock_.AdvanceTime(QuicTime::Delta::FromSeconds(10));
   EXPECT_CALL(visitor_, SendPing()).WillOnce(Invoke([this]() {
     connection_.SendControlFrame(QuicFrame(QuicPingFrame(1)));
   }));
   connection_.GetPingAlarm()->Fire();
   size_t padding_frame_count = writer_->padding_frames().size();
   EXPECT_EQ(padding_frame_count + 1u, writer_->frame_count());
   ASSERT_EQ(1u, writer_->ping_frames().size());
   writer_->Reset();

   EXPECT_CALL(visitor_, ShouldKeepConnectionAlive())
       .WillRepeatedly(Return(false));
   clock_.AdvanceTime(QuicTime::Delta::FromMilliseconds(5));
   SendAckPacketToPeer();

   EXPECT_FALSE(connection_.GetPingAlarm()->IsSet());
 }

 // Tests whether sending an MTU discovery packet to peer successfully causes the
 // maximum packet size to increase.
 TEST_P(QuicConnectionTest, SendMtuDiscoveryPacket) {
   if (connection_.SupportsMultiplePacketNumberSpaces()) {
     return;
   }
   EXPECT_TRUE(connection_.connected());

   // Send an MTU probe.
   const size_t new_mtu = kDefaultMaxPacketSize + 100;
   QuicByteCount mtu_probe_size;
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _))
       .WillOnce(SaveArg<3>(&mtu_probe_size));
   connection_.SendMtuDiscoveryPacket(new_mtu);
   EXPECT_EQ(new_mtu, mtu_probe_size);
   EXPECT_EQ(QuicPacketNumber(1u), creator_->packet_number());

   // QuicFramer::GetMaxPlaintextSize uses the smallest max plaintext size across
   // all encrypters. The initial encrypter used with IETF QUIC has a 16-byte
   // overhead, while the NullEncrypter used throughout this test has a 12-byte
   // overhead. This test tests behavior that relies on computing the packet size
   // correctly, so by unsetting the initial encrypter, we avoid having a
   // mismatch between the overheads for the encrypters used. In non-test
   // scenarios all encrypters used for a given connection have the same
   // overhead, either 12 bytes for ones using Google QUIC crypto, or 16 bytes
   // for ones using TLS.
   connection_.SetEncrypter(ENCRYPTION_INITIAL, nullptr);

   // Send more than MTU worth of data.  No acknowledgement was received so far,
   // so the MTU should be at its old value.
   const std::string data(kDefaultMaxPacketSize + 1, '.');
   QuicByteCount size_before_mtu_change;
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _))
       .Times(2)
       .WillOnce(SaveArg<3>(&size_before_mtu_change))
       .WillOnce(Return());
   connection_.SendStreamDataWithString(3, data, 0, FIN);
   EXPECT_EQ(QuicPacketNumber(3u), creator_->packet_number());
   EXPECT_EQ(kDefaultMaxPacketSize, size_before_mtu_change);

   // Acknowledge all packets so far.
   QuicAckFrame probe_ack = InitAckFrame(3);
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
   EXPECT_CALL(*send_algorithm_, OnCongestionEvent(true, _, _, _, _));
   ProcessAckPacket(&probe_ack);
   EXPECT_EQ(new_mtu, connection_.max_packet_length());

   // Send the same data again.  Check that it fits into a single packet now.
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(1);
   connection_.SendStreamDataWithString(3, data, 0, FIN);
   EXPECT_EQ(QuicPacketNumber(4u), creator_->packet_number());
 }

 // Tests whether MTU discovery does not happen when it is not explicitly enabled
 // by the connection options.
 TEST_P(QuicConnectionTest, MtuDiscoveryDisabled) {
   EXPECT_TRUE(connection_.connected());

   const QuicPacketCount packets_between_probes_base = 10;
   set_packets_between_probes_base(packets_between_probes_base);

   const QuicPacketCount number_of_packets = packets_between_probes_base * 2;
   for (QuicPacketCount i = 0; i < number_of_packets; i++) {
     SendStreamDataToPeer(3, ".", i, NO_FIN, nullptr);
     EXPECT_FALSE(connection_.GetMtuDiscoveryAlarm()->IsSet());
     EXPECT_EQ(0u, connection_.mtu_probe_count());
   }
 }

 // Tests whether MTU discovery works when all probes are acknowledged on the
 // first try.
 TEST_P(QuicConnectionTest, MtuDiscoveryEnabled) {
   EXPECT_TRUE(connection_.connected());

   // QuicFramer::GetMaxPlaintextSize uses the smallest max plaintext size across
   // all encrypters. The initial encrypter used with IETF QUIC has a 16-byte
   // overhead, while the NullEncrypter used throughout this test has a 12-byte
   // overhead. This test tests behavior that relies on computing the packet size
   // correctly, so by unsetting the initial encrypter, we avoid having a
   // mismatch between the overheads for the encrypters used. In non-test
   // scenarios all encrypters used for a given connection have the same
   // overhead, either 12 bytes for ones using Google QUIC crypto, or 16 bytes
   // for ones using TLS.
   connection_.SetEncrypter(ENCRYPTION_INITIAL, nullptr);

   const QuicPacketCount packets_between_probes_base = 5;
   set_packets_between_probes_base(packets_between_probes_base);

   connection_.EnablePathMtuDiscovery(send_algorithm_);

   // Send enough packets so that the next one triggers path MTU discovery.
   for (QuicPacketCount i = 0; i < packets_between_probes_base - 1; i++) {
     SendStreamDataToPeer(3, ".", i, NO_FIN, nullptr);
     ASSERT_FALSE(connection_.GetMtuDiscoveryAlarm()->IsSet());
   }

   // Trigger the probe.
   SendStreamDataToPeer(3, "!", packets_between_probes_base - 1, NO_FIN,
                        nullptr);
   ASSERT_TRUE(connection_.GetMtuDiscoveryAlarm()->IsSet());
   QuicByteCount probe_size;
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _))
       .WillOnce(SaveArg<3>(&probe_size));
   connection_.GetMtuDiscoveryAlarm()->Fire();
   if (GetQuicReloadableFlag(quic_mtu_discovery_v2)) {
     EXPECT_THAT(probe_size, InRange(connection_.max_packet_length(),
                                     kMtuDiscoveryTargetPacketSizeHigh));
   } else {
     EXPECT_EQ(kMtuDiscoveryTargetPacketSizeHigh, probe_size);
   }

   const QuicPacketNumber probe_packet_number =
       FirstSendingPacketNumber() + packets_between_probes_base;
   ASSERT_EQ(probe_packet_number, creator_->packet_number());

   // Acknowledge all packets sent so far.
   QuicAckFrame probe_ack = InitAckFrame(probe_packet_number);
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
   EXPECT_CALL(*send_algorithm_, OnCongestionEvent(true, _, _, _, _))
       .Times(AnyNumber());
   ProcessAckPacket(&probe_ack);
   EXPECT_EQ(probe_size, connection_.max_packet_length());
   EXPECT_EQ(0u, connection_.GetBytesInFlight());

   EXPECT_EQ(1u, connection_.mtu_probe_count());

   if (!GetQuicReloadableFlag(quic_mtu_discovery_v2)) {
     // Send more packets, and ensure that none of them sets the alarm.
     for (QuicPacketCount i = 0; i < 4 * packets_between_probes_base; i++) {
       SendStreamDataToPeer(3, ".", packets_between_probes_base + i, NO_FIN,
                            nullptr);
       ASSERT_FALSE(connection_.GetMtuDiscoveryAlarm()->IsSet());
     }

     return;
   }

   QuicStreamOffset stream_offset = packets_between_probes_base;
   for (size_t num_probes = 1; num_probes < kMtuDiscoveryAttempts;
        ++num_probes) {
     // Send just enough packets without triggering the next probe.
     for (QuicPacketCount i = 0;
          i < (packets_between_probes_base << num_probes) - 1; ++i) {
       SendStreamDataToPeer(3, ".", stream_offset++, NO_FIN, nullptr);
       ASSERT_FALSE(connection_.GetMtuDiscoveryAlarm()->IsSet());
     }

     // Trigger the next probe.
     SendStreamDataToPeer(3, "!", stream_offset++, NO_FIN, nullptr);
     ASSERT_TRUE(connection_.GetMtuDiscoveryAlarm()->IsSet());
     QuicByteCount new_probe_size;
     EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _))
         .WillOnce(SaveArg<3>(&new_probe_size));
     connection_.GetMtuDiscoveryAlarm()->Fire();
     EXPECT_THAT(new_probe_size,
                 InRange(probe_size, kMtuDiscoveryTargetPacketSizeHigh));
     EXPECT_EQ(num_probes + 1, connection_.mtu_probe_count());

     // Acknowledge all packets sent so far.
     QuicAckFrame probe_ack = InitAckFrame(creator_->packet_number());
     ProcessAckPacket(&probe_ack);
     EXPECT_EQ(new_probe_size, connection_.max_packet_length());
     EXPECT_EQ(0u, connection_.GetBytesInFlight());

     probe_size = new_probe_size;
   }

   // The last probe size should be equal to the target.
   EXPECT_EQ(probe_size, kMtuDiscoveryTargetPacketSizeHigh);
 }

 // Simulate the case where the first attempt to send a probe is write blocked,
 // and after unblock, the second attempt returns a MSG_TOO_BIG error.
 TEST_P(QuicConnectionTest, MtuDiscoveryWriteBlocked) {
   EXPECT_TRUE(connection_.connected());

   connection_.SetEncrypter(ENCRYPTION_INITIAL, nullptr);

   const QuicPacketCount packets_between_probes_base = 5;
   set_packets_between_probes_base(packets_between_probes_base);

   connection_.EnablePathMtuDiscovery(send_algorithm_);

   // Send enough packets so that the next one triggers path MTU discovery.
   for (QuicPacketCount i = 0; i < packets_between_probes_base - 1; i++) {
     SendStreamDataToPeer(3, ".", i, NO_FIN, nullptr);
     ASSERT_FALSE(connection_.GetMtuDiscoveryAlarm()->IsSet());
   }

   QuicByteCount original_max_packet_length = connection_.max_packet_length();

   // Trigger the probe.
   SendStreamDataToPeer(3, "!", packets_between_probes_base - 1, NO_FIN,
                        nullptr);
   ASSERT_TRUE(connection_.GetMtuDiscoveryAlarm()->IsSet());
   if (GetQuicReloadableFlag(quic_treat_queued_packets_as_sent)) {
     EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _));
   }
   BlockOnNextWrite();
   EXPECT_EQ(0u, connection_.NumQueuedPackets());
   connection_.GetMtuDiscoveryAlarm()->Fire();
   EXPECT_EQ(1u, connection_.mtu_probe_count());
   EXPECT_EQ(1u, connection_.NumQueuedPackets());
   ASSERT_TRUE(connection_.connected());

   writer_->SetWritable();
   SimulateNextPacketTooLarge();
   connection_.OnCanWrite();
   EXPECT_EQ(0u, connection_.NumQueuedPackets());
   EXPECT_EQ(original_max_packet_length, connection_.max_packet_length());
   EXPECT_TRUE(connection_.connected());
 }

 // Tests whether MTU discovery works correctly when the probes never get
 // acknowledged.
 TEST_P(QuicConnectionTest, MtuDiscoveryFailed) {
   EXPECT_TRUE(connection_.connected());

   // Lower the number of probes between packets in order to make the test go
   // much faster.
   const QuicPacketCount packets_between_probes_base = 5;
   set_packets_between_probes_base(packets_between_probes_base);

   connection_.EnablePathMtuDiscovery(send_algorithm_);

   const QuicTime::Delta rtt = QuicTime::Delta::FromMilliseconds(100);

   EXPECT_EQ(packets_between_probes_base,
             QuicConnectionPeer::GetPacketsBetweenMtuProbes(&connection_));

   // This tests sends more packets than strictly necessary to make sure that if
   // the connection was to send more discovery packets than needed, those would
   // get caught as well.
   const QuicPacketCount number_of_packets =
       packets_between_probes_base * (1 << (kMtuDiscoveryAttempts + 1));
   std::vector<QuicPacketNumber> mtu_discovery_packets;
   // Called by the first ack.
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
   // Called on many acks.
   EXPECT_CALL(*send_algorithm_, OnCongestionEvent(true, _, _, _, _))
       .Times(AnyNumber());
   for (QuicPacketCount i = 0; i < number_of_packets; i++) {
     SendStreamDataToPeer(3, "!", i, NO_FIN, nullptr);
     clock_.AdvanceTime(rtt);

     // Receive an ACK, which marks all data packets as received, and all MTU
     // discovery packets as missing.

     QuicAckFrame ack;

     if (!mtu_discovery_packets.empty()) {
       QuicPacketNumber min_packet = *min_element(mtu_discovery_packets.begin(),
                                                  mtu_discovery_packets.end());
       QuicPacketNumber max_packet = *max_element(mtu_discovery_packets.begin(),
                                                  mtu_discovery_packets.end());
       ack.packets.AddRange(QuicPacketNumber(1), min_packet);
       ack.packets.AddRange(QuicPacketNumber(max_packet + 1),
                            creator_->packet_number() + 1);
       ack.largest_acked = creator_->packet_number();

     } else {
       ack.packets.AddRange(QuicPacketNumber(1), creator_->packet_number() + 1);
       ack.largest_acked = creator_->packet_number();
     }

     ProcessAckPacket(&ack);

     // Trigger MTU probe if it would be scheduled now.
     if (!connection_.GetMtuDiscoveryAlarm()->IsSet()) {
       continue;
     }

     // Fire the alarm.  The alarm should cause a packet to be sent.
     EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _));
     connection_.GetMtuDiscoveryAlarm()->Fire();
     // Record the packet number of the MTU discovery packet in order to
     // mark it as NACK'd.
     mtu_discovery_packets.push_back(creator_->packet_number());
   }

   // Ensure the number of packets between probes grows exponentially by checking
   // it against the closed-form expression for the packet number.
   ASSERT_EQ(kMtuDiscoveryAttempts, mtu_discovery_packets.size());
   for (uint64_t i = 0; i < kMtuDiscoveryAttempts; i++) {
     // 2^0 + 2^1 + 2^2 + ... + 2^n = 2^(n + 1) - 1
     const QuicPacketCount packets_between_probes =
         packets_between_probes_base * ((1 << (i + 1)) - 1);
     EXPECT_EQ(QuicPacketNumber(packets_between_probes + (i + 1)),
               mtu_discovery_packets[i]);
   }

   EXPECT_FALSE(connection_.GetMtuDiscoveryAlarm()->IsSet());
   EXPECT_EQ(kDefaultMaxPacketSize, connection_.max_packet_length());
   EXPECT_EQ(kMtuDiscoveryAttempts, connection_.mtu_probe_count());
 }

 // Probe 3 times, the first one succeeds, then fails, then succeeds again.
 TEST_P(QuicConnectionTest, MtuDiscoverySecondProbeFailed) {
   if (!GetQuicReloadableFlag(quic_mtu_discovery_v2)) {
     return;
   }
   EXPECT_TRUE(connection_.connected());

   // QuicFramer::GetMaxPlaintextSize uses the smallest max plaintext size across
   // all encrypters. The initial encrypter used with IETF QUIC has a 16-byte
   // overhead, while the NullEncrypter used throughout this test has a 12-byte
   // overhead. This test tests behavior that relies on computing the packet size
   // correctly, so by unsetting the initial encrypter, we avoid having a
   // mismatch between the overheads for the encrypters used. In non-test
   // scenarios all encrypters used for a given connection have the same
   // overhead, either 12 bytes for ones using Google QUIC crypto, or 16 bytes
   // for ones using TLS.
   connection_.SetEncrypter(ENCRYPTION_INITIAL, nullptr);

   const QuicPacketCount packets_between_probes_base = 5;
   set_packets_between_probes_base(packets_between_probes_base);

   connection_.EnablePathMtuDiscovery(send_algorithm_);

   // Send enough packets so that the next one triggers path MTU discovery.
   QuicStreamOffset stream_offset = 0;
   for (QuicPacketCount i = 0; i < packets_between_probes_base - 1; i++) {
     SendStreamDataToPeer(3, ".", stream_offset++, NO_FIN, nullptr);
     ASSERT_FALSE(connection_.GetMtuDiscoveryAlarm()->IsSet());
   }

   // Trigger the probe.
   SendStreamDataToPeer(3, "!", packets_between_probes_base - 1, NO_FIN,
                        nullptr);
   ASSERT_TRUE(connection_.GetMtuDiscoveryAlarm()->IsSet());
   QuicByteCount probe_size;
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _))
       .WillOnce(SaveArg<3>(&probe_size));
   connection_.GetMtuDiscoveryAlarm()->Fire();
   EXPECT_THAT(probe_size, InRange(connection_.max_packet_length(),
                                   kMtuDiscoveryTargetPacketSizeHigh));

   const QuicPacketNumber probe_packet_number =
       FirstSendingPacketNumber() + packets_between_probes_base;
   ASSERT_EQ(probe_packet_number, creator_->packet_number());

   // Acknowledge all packets sent so far.
   QuicAckFrame first_ack = InitAckFrame(probe_packet_number);
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
   EXPECT_CALL(*send_algorithm_, OnCongestionEvent(true, _, _, _, _))
       .Times(AnyNumber());
   ProcessAckPacket(&first_ack);
   EXPECT_EQ(probe_size, connection_.max_packet_length());
   EXPECT_EQ(0u, connection_.GetBytesInFlight());

   EXPECT_EQ(1u, connection_.mtu_probe_count());

   // Send just enough packets without triggering the second probe.
   for (QuicPacketCount i = 0; i < (packets_between_probes_base << 1) - 1; ++i) {
     SendStreamDataToPeer(3, ".", stream_offset++, NO_FIN, nullptr);
     ASSERT_FALSE(connection_.GetMtuDiscoveryAlarm()->IsSet());
   }

   // Trigger the second probe.
   SendStreamDataToPeer(3, "!", stream_offset++, NO_FIN, nullptr);
   ASSERT_TRUE(connection_.GetMtuDiscoveryAlarm()->IsSet());
   QuicByteCount second_probe_size;
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _))
       .WillOnce(SaveArg<3>(&second_probe_size));
   connection_.GetMtuDiscoveryAlarm()->Fire();
   EXPECT_THAT(second_probe_size,
               InRange(probe_size, kMtuDiscoveryTargetPacketSizeHigh));
   EXPECT_EQ(2u, connection_.mtu_probe_count());

   // Acknowledge all packets sent so far, except the second probe.
   QuicPacketNumber second_probe_packet_number = creator_->packet_number();
   QuicAckFrame second_ack = InitAckFrame(second_probe_packet_number - 1);
   ProcessAckPacket(&first_ack);
   EXPECT_EQ(probe_size, connection_.max_packet_length());

   // Send just enough packets without triggering the third probe.
   for (QuicPacketCount i = 0; i < (packets_between_probes_base << 2) - 1; ++i) {
     SendStreamDataToPeer(3, "@", stream_offset++, NO_FIN, nullptr);
     ASSERT_FALSE(connection_.GetMtuDiscoveryAlarm()->IsSet());
   }

   // Trigger the third probe.
   SendStreamDataToPeer(3, "#", stream_offset++, NO_FIN, nullptr);
   ASSERT_TRUE(connection_.GetMtuDiscoveryAlarm()->IsSet());
   QuicByteCount third_probe_size;
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _))
       .WillOnce(SaveArg<3>(&third_probe_size));
   connection_.GetMtuDiscoveryAlarm()->Fire();
   EXPECT_THAT(third_probe_size, InRange(probe_size, second_probe_size));
   EXPECT_EQ(3u, connection_.mtu_probe_count());

   // Acknowledge all packets sent so far, except the second probe.
   QuicAckFrame third_ack =
       ConstructAckFrame(creator_->packet_number(), second_probe_packet_number);
   ProcessAckPacket(&third_ack);
   EXPECT_EQ(third_probe_size, connection_.max_packet_length());
 }

 // Tests whether MTU discovery works when the writer has a limit on how large a
 // packet can be.
 TEST_P(QuicConnectionTest, MtuDiscoveryWriterLimited) {
   EXPECT_TRUE(connection_.connected());

   // QuicFramer::GetMaxPlaintextSize uses the smallest max plaintext size across
   // all encrypters. The initial encrypter used with IETF QUIC has a 16-byte
   // overhead, while the NullEncrypter used throughout this test has a 12-byte
   // overhead. This test tests behavior that relies on computing the packet size
   // correctly, so by unsetting the initial encrypter, we avoid having a
   // mismatch between the overheads for the encrypters used. In non-test
   // scenarios all encrypters used for a given connection have the same
   // overhead, either 12 bytes for ones using Google QUIC crypto, or 16 bytes
   // for ones using TLS.
   connection_.SetEncrypter(ENCRYPTION_INITIAL, nullptr);

   const QuicByteCount mtu_limit = kMtuDiscoveryTargetPacketSizeHigh - 1;
   writer_->set_max_packet_size(mtu_limit);

   const QuicPacketCount packets_between_probes_base = 5;
   set_packets_between_probes_base(packets_between_probes_base);

   connection_.EnablePathMtuDiscovery(send_algorithm_);

   // Send enough packets so that the next one triggers path MTU discovery.
   for (QuicPacketCount i = 0; i < packets_between_probes_base - 1; i++) {
     SendStreamDataToPeer(3, ".", i, NO_FIN, nullptr);
     ASSERT_FALSE(connection_.GetMtuDiscoveryAlarm()->IsSet());
   }

   // Trigger the probe.
   SendStreamDataToPeer(3, "!", packets_between_probes_base - 1, NO_FIN,
                        nullptr);
   ASSERT_TRUE(connection_.GetMtuDiscoveryAlarm()->IsSet());
   QuicByteCount probe_size;
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _))
       .WillOnce(SaveArg<3>(&probe_size));
   connection_.GetMtuDiscoveryAlarm()->Fire();
   if (GetQuicReloadableFlag(quic_mtu_discovery_v2)) {
     EXPECT_THAT(probe_size,
                 InRange(connection_.max_packet_length(), mtu_limit));
   } else {
     EXPECT_EQ(mtu_limit, probe_size);
   }

   const QuicPacketNumber probe_sequence_number =
       FirstSendingPacketNumber() + packets_between_probes_base;
   ASSERT_EQ(probe_sequence_number, creator_->packet_number());

   // Acknowledge all packets sent so far.
   QuicAckFrame probe_ack = InitAckFrame(probe_sequence_number);
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
   EXPECT_CALL(*send_algorithm_, OnCongestionEvent(true, _, _, _, _))
       .Times(AnyNumber());
   ProcessAckPacket(&probe_ack);
   EXPECT_EQ(probe_size, connection_.max_packet_length());
   EXPECT_EQ(0u, connection_.GetBytesInFlight());

   EXPECT_EQ(1u, connection_.mtu_probe_count());

   if (!GetQuicReloadableFlag(quic_mtu_discovery_v2)) {
     // Send more packets, and ensure that none of them sets the alarm.
     for (QuicPacketCount i = 0; i < 4 * packets_between_probes_base; i++) {
       SendStreamDataToPeer(3, ".", packets_between_probes_base + i, NO_FIN,
                            nullptr);
       ASSERT_FALSE(connection_.GetMtuDiscoveryAlarm()->IsSet());
     }

     return;
   }

   QuicStreamOffset stream_offset = packets_between_probes_base;
   for (size_t num_probes = 1; num_probes < kMtuDiscoveryAttempts;
        ++num_probes) {
     // Send just enough packets without triggering the next probe.
     for (QuicPacketCount i = 0;
          i < (packets_between_probes_base << num_probes) - 1; ++i) {
       SendStreamDataToPeer(3, ".", stream_offset++, NO_FIN, nullptr);
       ASSERT_FALSE(connection_.GetMtuDiscoveryAlarm()->IsSet());
     }

     // Trigger the next probe.
     SendStreamDataToPeer(3, "!", stream_offset++, NO_FIN, nullptr);
     ASSERT_TRUE(connection_.GetMtuDiscoveryAlarm()->IsSet());
     QuicByteCount new_probe_size;
     EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _))
         .WillOnce(SaveArg<3>(&new_probe_size));
     connection_.GetMtuDiscoveryAlarm()->Fire();
     EXPECT_THAT(new_probe_size, InRange(probe_size, mtu_limit));
     EXPECT_EQ(num_probes + 1, connection_.mtu_probe_count());

     // Acknowledge all packets sent so far.
     QuicAckFrame probe_ack = InitAckFrame(creator_->packet_number());
     ProcessAckPacket(&probe_ack);
     EXPECT_EQ(new_probe_size, connection_.max_packet_length());
     EXPECT_EQ(0u, connection_.GetBytesInFlight());

     probe_size = new_probe_size;
   }

   // The last probe size should be equal to the target.
   EXPECT_EQ(probe_size, mtu_limit);
 }

 // Tests whether MTU discovery works when the writer returns an error despite
 // advertising higher packet length.
 TEST_P(QuicConnectionTest, MtuDiscoveryWriterFailed) {
   EXPECT_TRUE(connection_.connected());

   const QuicByteCount mtu_limit = kMtuDiscoveryTargetPacketSizeHigh - 1;
   const QuicByteCount initial_mtu = connection_.max_packet_length();
   EXPECT_LT(initial_mtu, mtu_limit);
   writer_->set_max_packet_size(mtu_limit);

   const QuicPacketCount packets_between_probes_base = 5;
   set_packets_between_probes_base(packets_between_probes_base);

   connection_.EnablePathMtuDiscovery(send_algorithm_);

   // Send enough packets so that the next one triggers path MTU discovery.
   for (QuicPacketCount i = 0; i < packets_between_probes_base - 1; i++) {
     SendStreamDataToPeer(3, ".", i, NO_FIN, nullptr);
     ASSERT_FALSE(connection_.GetMtuDiscoveryAlarm()->IsSet());
   }

   // Trigger the probe.
   SendStreamDataToPeer(3, "!", packets_between_probes_base - 1, NO_FIN,
                        nullptr);
   ASSERT_TRUE(connection_.GetMtuDiscoveryAlarm()->IsSet());
   writer_->SimulateNextPacketTooLarge();
   connection_.GetMtuDiscoveryAlarm()->Fire();
   ASSERT_TRUE(connection_.connected());

   // Send more data.
   QuicPacketNumber probe_number = creator_->packet_number();
   QuicPacketCount extra_packets = packets_between_probes_base * 3;
   for (QuicPacketCount i = 0; i < extra_packets; i++) {
     connection_.EnsureWritableAndSendStreamData5();
     ASSERT_FALSE(connection_.GetMtuDiscoveryAlarm()->IsSet());
   }

   // Acknowledge all packets sent so far, except for the lost probe.
   QuicAckFrame probe_ack =
       ConstructAckFrame(creator_->packet_number(), probe_number);
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
   EXPECT_CALL(*send_algorithm_, OnCongestionEvent(true, _, _, _, _));
   ProcessAckPacket(&probe_ack);
   EXPECT_EQ(initial_mtu, connection_.max_packet_length());

   // Send more packets, and ensure that none of them sets the alarm.
   for (QuicPacketCount i = 0; i < 4 * packets_between_probes_base; i++) {
     connection_.EnsureWritableAndSendStreamData5();
     ASSERT_FALSE(connection_.GetMtuDiscoveryAlarm()->IsSet());
   }

   EXPECT_EQ(initial_mtu, connection_.max_packet_length());
   EXPECT_EQ(1u, connection_.mtu_probe_count());
 }

 TEST_P(QuicConnectionTest, NoMtuDiscoveryAfterConnectionClosed) {
   EXPECT_TRUE(connection_.connected());

   const QuicPacketCount packets_between_probes_base = 10;
   set_packets_between_probes_base(packets_between_probes_base);

   connection_.EnablePathMtuDiscovery(send_algorithm_);

   // Send enough packets so that the next one triggers path MTU discovery.
   for (QuicPacketCount i = 0; i < packets_between_probes_base - 1; i++) {
     SendStreamDataToPeer(3, ".", i, NO_FIN, nullptr);
     ASSERT_FALSE(connection_.GetMtuDiscoveryAlarm()->IsSet());
   }

   SendStreamDataToPeer(3, "!", packets_between_probes_base - 1, NO_FIN,
                        nullptr);
   EXPECT_TRUE(connection_.GetMtuDiscoveryAlarm()->IsSet());

   EXPECT_CALL(visitor_, OnConnectionClosed(_, _));
   connection_.CloseConnection(QUIC_PEER_GOING_AWAY, "no reason",
                               ConnectionCloseBehavior::SILENT_CLOSE);
   EXPECT_FALSE(connection_.GetMtuDiscoveryAlarm()->IsSet());
 }

 TEST_P(QuicConnectionTest, TimeoutAfterSend) {
   EXPECT_TRUE(connection_.connected());
   EXPECT_CALL(*send_algorithm_, SetFromConfig(_, _));
   QuicConfig config;
   connection_.SetFromConfig(config);
   EXPECT_FALSE(QuicConnectionPeer::IsSilentCloseEnabled(&connection_));

   const QuicTime::Delta initial_idle_timeout =
       QuicTime::Delta::FromSeconds(kInitialIdleTimeoutSecs - 1);
   const QuicTime::Delta five_ms = QuicTime::Delta::FromMilliseconds(5);
   QuicTime default_timeout = clock_.ApproximateNow() + initial_idle_timeout;

   // When we send a packet, the timeout will change to 5ms +
   // kInitialIdleTimeoutSecs.
   clock_.AdvanceTime(five_ms);
   SendStreamDataToPeer(
       GetNthClientInitiatedStreamId(1, connection_.transport_version()), "foo",
       0, FIN, nullptr);
   EXPECT_EQ(default_timeout, connection_.GetTimeoutAlarm()->deadline());

   // Now send more data. This will not move the timeout because
   // no data has been received since the previous write.
   clock_.AdvanceTime(five_ms);
   SendStreamDataToPeer(
       GetNthClientInitiatedStreamId(1, connection_.transport_version()), "foo",
       3, FIN, nullptr);
   EXPECT_EQ(default_timeout, connection_.GetTimeoutAlarm()->deadline());

   // The original alarm will fire.  We should not time out because we had a
   // network event at t=5ms.  The alarm will reregister.
   clock_.AdvanceTime(initial_idle_timeout - five_ms - five_ms);
   EXPECT_EQ(default_timeout, clock_.ApproximateNow());
   connection_.GetTimeoutAlarm()->Fire();
   EXPECT_TRUE(connection_.GetTimeoutAlarm()->IsSet());
   EXPECT_TRUE(connection_.connected());
   EXPECT_EQ(default_timeout + five_ms,
             connection_.GetTimeoutAlarm()->deadline());

   // This time, we should time out.
   EXPECT_CALL(visitor_,
               OnConnectionClosed(_, ConnectionCloseSource::FROM_SELF));
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(AtLeast(1));
   clock_.AdvanceTime(five_ms);
   EXPECT_EQ(default_timeout + five_ms, clock_.ApproximateNow());
   connection_.GetTimeoutAlarm()->Fire();
   EXPECT_FALSE(connection_.GetTimeoutAlarm()->IsSet());
   EXPECT_FALSE(connection_.connected());
   TestConnectionCloseQuicErrorCode(QUIC_NETWORK_IDLE_TIMEOUT);
 }

 TEST_P(QuicConnectionTest, TimeoutAfterRetransmission) {
   if (connection_.PtoEnabled()) {
     return;
   }
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
   EXPECT_TRUE(connection_.connected());
   EXPECT_CALL(*send_algorithm_, SetFromConfig(_, _));
   QuicConfig config;
   connection_.SetFromConfig(config);
   EXPECT_FALSE(QuicConnectionPeer::IsSilentCloseEnabled(&connection_));

   const QuicTime start_time = clock_.Now();
   const QuicTime::Delta initial_idle_timeout =
       QuicTime::Delta::FromSeconds(kInitialIdleTimeoutSecs - 1);
   QuicTime default_timeout = clock_.Now() + initial_idle_timeout;

   connection_.SetMaxTailLossProbes(0);
   const QuicTime default_retransmission_time =
       start_time + DefaultRetransmissionTime();

   ASSERT_LT(default_retransmission_time, default_timeout);

   // When we send a packet, the timeout will change to 5 ms +
   // kInitialIdleTimeoutSecs (but it will not reschedule the alarm).
   const QuicTime::Delta five_ms = QuicTime::Delta::FromMilliseconds(5);
   const QuicTime send_time = start_time + five_ms;
   clock_.AdvanceTime(five_ms);
   ASSERT_EQ(send_time, clock_.Now());
   SendStreamDataToPeer(
       GetNthClientInitiatedStreamId(1, connection_.transport_version()), "foo",
       0, FIN, nullptr);
   EXPECT_EQ(default_timeout, connection_.GetTimeoutAlarm()->deadline());

   // Move forward 5 ms and receive a packet, which will move the timeout
   // forward 5 ms more (but will not reschedule the alarm).
   const QuicTime receive_time = send_time + five_ms;
   clock_.AdvanceTime(receive_time - clock_.Now());
   ASSERT_EQ(receive_time, clock_.Now());
   ProcessPacket(1);

   // Now move forward to the retransmission time and retransmit the
   // packet, which should move the timeout forward again (but will not
   // reschedule the alarm).
   EXPECT_EQ(default_retransmission_time + five_ms,
             connection_.GetRetransmissionAlarm()->deadline());
   // Simulate the retransmission alarm firing.
   const QuicTime rto_time = send_time + DefaultRetransmissionTime();
   const QuicTime final_timeout = rto_time + initial_idle_timeout;
   clock_.AdvanceTime(rto_time - clock_.Now());
   ASSERT_EQ(rto_time, clock_.Now());
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, QuicPacketNumber(2u), _, _));
   connection_.GetRetransmissionAlarm()->Fire();

   // Advance to the original timeout and fire the alarm. The connection should
   // timeout, and the alarm should be registered based on the time of the
   // retransmission.
   clock_.AdvanceTime(default_timeout - clock_.Now());
   ASSERT_EQ(default_timeout.ToDebuggingValue(),
             clock_.Now().ToDebuggingValue());
   EXPECT_EQ(default_timeout, clock_.Now());
   connection_.GetTimeoutAlarm()->Fire();
   EXPECT_TRUE(connection_.GetTimeoutAlarm()->IsSet());
   EXPECT_TRUE(connection_.connected());
   ASSERT_EQ(final_timeout.ToDebuggingValue(),
             connection_.GetTimeoutAlarm()->deadline().ToDebuggingValue());

   // This time, we should time out.
   EXPECT_CALL(visitor_,
               OnConnectionClosed(_, ConnectionCloseSource::FROM_SELF));
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(AtLeast(1));
   clock_.AdvanceTime(final_timeout - clock_.Now());
   EXPECT_EQ(connection_.GetTimeoutAlarm()->deadline(), clock_.Now());
   EXPECT_EQ(final_timeout, clock_.Now());
   connection_.GetTimeoutAlarm()->Fire();
   EXPECT_FALSE(connection_.GetTimeoutAlarm()->IsSet());
   EXPECT_FALSE(connection_.connected());
   TestConnectionCloseQuicErrorCode(QUIC_NETWORK_IDLE_TIMEOUT);
 }

 TEST_P(QuicConnectionTest, NewTimeoutAfterSendSilentClose) {
   // Same test as above, but complete a handshake which enables silent close,
   // causing no connection close packet to be sent.
   EXPECT_TRUE(connection_.connected());
   EXPECT_CALL(*send_algorithm_, SetFromConfig(_, _));
   QuicConfig config;

   // Create a handshake message that also enables silent close.
   CryptoHandshakeMessage msg;
   std::string error_details;
   QuicConfig client_config;
   client_config.SetInitialStreamFlowControlWindowToSend(
       kInitialStreamFlowControlWindowForTest);
   client_config.SetInitialSessionFlowControlWindowToSend(
       kInitialSessionFlowControlWindowForTest);
   client_config.SetIdleNetworkTimeout(
       QuicTime::Delta::FromSeconds(kDefaultIdleTimeoutSecs),
       QuicTime::Delta::FromSeconds(kDefaultIdleTimeoutSecs));
   client_config.ToHandshakeMessage(&msg, connection_.transport_version());
   const QuicErrorCode error =
       config.ProcessPeerHello(msg, CLIENT, &error_details);
   EXPECT_EQ(QUIC_NO_ERROR, error);

   connection_.SetFromConfig(config);
   EXPECT_TRUE(QuicConnectionPeer::IsSilentCloseEnabled(&connection_));

   const QuicTime::Delta default_idle_timeout =
       QuicTime::Delta::FromSeconds(kDefaultIdleTimeoutSecs - 1);
   const QuicTime::Delta five_ms = QuicTime::Delta::FromMilliseconds(5);
   QuicTime default_timeout = clock_.ApproximateNow() + default_idle_timeout;

   // When we send a packet, the timeout will change to 5ms +
   // kInitialIdleTimeoutSecs.
   clock_.AdvanceTime(five_ms);
   SendStreamDataToPeer(
       GetNthClientInitiatedStreamId(1, connection_.transport_version()), "foo",
       0, FIN, nullptr);
   EXPECT_EQ(default_timeout, connection_.GetTimeoutAlarm()->deadline());

   // Now send more data. This will not move the timeout because
   // no data has been received since the previous write.
   clock_.AdvanceTime(five_ms);
   SendStreamDataToPeer(
       GetNthClientInitiatedStreamId(1, connection_.transport_version()), "foo",
       3, FIN, nullptr);
   EXPECT_EQ(default_timeout, connection_.GetTimeoutAlarm()->deadline());

   // The original alarm will fire.  We should not time out because we had a
   // network event at t=5ms.  The alarm will reregister.
   clock_.AdvanceTime(default_idle_timeout - five_ms - five_ms);
   EXPECT_EQ(default_timeout, clock_.ApproximateNow());
   connection_.GetTimeoutAlarm()->Fire();
   EXPECT_TRUE(connection_.GetTimeoutAlarm()->IsSet());
   EXPECT_TRUE(connection_.connected());
   EXPECT_EQ(default_timeout + five_ms,
             connection_.GetTimeoutAlarm()->deadline());

   // This time, we should time out.
   // This results in a SILENT_CLOSE, so the writer will not be invoked
   // and will not save the frame. Grab the frame from OnConnectionClosed
   // directly.
   EXPECT_CALL(visitor_, OnConnectionClosed(_, ConnectionCloseSource::FROM_SELF))
       .WillOnce(Invoke(this, &QuicConnectionTest::SaveConnectionCloseFrame));

   clock_.AdvanceTime(five_ms);
   EXPECT_EQ(default_timeout + five_ms, clock_.ApproximateNow());
   connection_.GetTimeoutAlarm()->Fire();
   EXPECT_FALSE(connection_.GetTimeoutAlarm()->IsSet());
   EXPECT_FALSE(connection_.connected());
   EXPECT_EQ(1, connection_close_frame_count_);
   EXPECT_EQ(QUIC_NETWORK_IDLE_TIMEOUT,
             saved_connection_close_frame_.quic_error_code);
 }

 TEST_P(QuicConnectionTest, TimeoutAfterSendSilentCloseAndTLP) {
   if (connection_.PtoEnabled()) {
     return;
   }
   // Same test as above, but complete a handshake which enables silent close,
   // but sending TLPs causes the connection close to be sent.
   EXPECT_TRUE(connection_.connected());
   EXPECT_CALL(*send_algorithm_, SetFromConfig(_, _));
   QuicConfig config;

   // Create a handshake message that also enables silent close.
   CryptoHandshakeMessage msg;
   std::string error_details;
   QuicConfig client_config;
   client_config.SetInitialStreamFlowControlWindowToSend(
       kInitialStreamFlowControlWindowForTest);
   client_config.SetInitialSessionFlowControlWindowToSend(
       kInitialSessionFlowControlWindowForTest);
   client_config.SetIdleNetworkTimeout(
       QuicTime::Delta::FromSeconds(kDefaultIdleTimeoutSecs),
       QuicTime::Delta::FromSeconds(kDefaultIdleTimeoutSecs));
   client_config.ToHandshakeMessage(&msg, connection_.transport_version());
   const QuicErrorCode error =
       config.ProcessPeerHello(msg, CLIENT, &error_details);
   EXPECT_EQ(QUIC_NO_ERROR, error);

   connection_.SetFromConfig(config);
   EXPECT_TRUE(QuicConnectionPeer::IsSilentCloseEnabled(&connection_));

   const QuicTime::Delta default_idle_timeout =
       QuicTime::Delta::FromSeconds(kDefaultIdleTimeoutSecs - 1);
   const QuicTime::Delta five_ms = QuicTime::Delta::FromMilliseconds(5);
   QuicTime default_timeout = clock_.ApproximateNow() + default_idle_timeout;

   // When we send a packet, the timeout will change to 5ms +
   // kInitialIdleTimeoutSecs.
   clock_.AdvanceTime(five_ms);
   SendStreamDataToPeer(
       GetNthClientInitiatedStreamId(1, connection_.transport_version()), "foo",
       0, FIN, nullptr);
   EXPECT_EQ(default_timeout, connection_.GetTimeoutAlarm()->deadline());

   // Retransmit the packet via tail loss probe.
   clock_.AdvanceTime(connection_.GetRetransmissionAlarm()->deadline() -
                      clock_.Now());
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, QuicPacketNumber(2u), _, _));
   connection_.GetRetransmissionAlarm()->Fire();

   // This time, we should time out and send a connection close due to the TLP.
   EXPECT_CALL(visitor_,
               OnConnectionClosed(_, ConnectionCloseSource::FROM_SELF));
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(AtLeast(1));
   clock_.AdvanceTime(connection_.GetTimeoutAlarm()->deadline() -
                      clock_.ApproximateNow() + five_ms);
   connection_.GetTimeoutAlarm()->Fire();
   EXPECT_FALSE(connection_.GetTimeoutAlarm()->IsSet());
   EXPECT_FALSE(connection_.connected());
   TestConnectionCloseQuicErrorCode(QUIC_NETWORK_IDLE_TIMEOUT);
 }

 TEST_P(QuicConnectionTest, TimeoutAfterSendSilentCloseWithOpenStreams) {
   // Same test as above, but complete a handshake which enables silent close,
   // but having open streams causes the connection close to be sent.
   EXPECT_TRUE(connection_.connected());
   EXPECT_CALL(*send_algorithm_, SetFromConfig(_, _));
   QuicConfig config;

   // Create a handshake message that also enables silent close.
   CryptoHandshakeMessage msg;
   std::string error_details;
   QuicConfig client_config;
   client_config.SetInitialStreamFlowControlWindowToSend(
       kInitialStreamFlowControlWindowForTest);
   client_config.SetInitialSessionFlowControlWindowToSend(
       kInitialSessionFlowControlWindowForTest);
   client_config.SetIdleNetworkTimeout(
       QuicTime::Delta::FromSeconds(kDefaultIdleTimeoutSecs),
       QuicTime::Delta::FromSeconds(kDefaultIdleTimeoutSecs));
   client_config.ToHandshakeMessage(&msg, connection_.transport_version());
   const QuicErrorCode error =
       config.ProcessPeerHello(msg, CLIENT, &error_details);
   EXPECT_EQ(QUIC_NO_ERROR, error);

   connection_.SetFromConfig(config);
   EXPECT_TRUE(QuicConnectionPeer::IsSilentCloseEnabled(&connection_));

   const QuicTime::Delta default_idle_timeout =
       QuicTime::Delta::FromSeconds(kDefaultIdleTimeoutSecs - 1);
   const QuicTime::Delta five_ms = QuicTime::Delta::FromMilliseconds(5);
   QuicTime default_timeout = clock_.ApproximateNow() + default_idle_timeout;

   // When we send a packet, the timeout will change to 5ms +
   // kInitialIdleTimeoutSecs.
   clock_.AdvanceTime(five_ms);
   SendStreamDataToPeer(
       GetNthClientInitiatedStreamId(1, connection_.transport_version()), "foo",
       0, FIN, nullptr);
   EXPECT_EQ(default_timeout, connection_.GetTimeoutAlarm()->deadline());

   // Indicate streams are still open.
   EXPECT_CALL(visitor_, ShouldKeepConnectionAlive())
       .WillRepeatedly(Return(true));

   // This time, we should time out and send a connection close due to the TLP.
   EXPECT_CALL(visitor_,
               OnConnectionClosed(_, ConnectionCloseSource::FROM_SELF));
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(AtLeast(1));
   clock_.AdvanceTime(connection_.GetTimeoutAlarm()->deadline() -
                      clock_.ApproximateNow() + five_ms);
   connection_.GetTimeoutAlarm()->Fire();
   EXPECT_FALSE(connection_.GetTimeoutAlarm()->IsSet());
   EXPECT_FALSE(connection_.connected());
   TestConnectionCloseQuicErrorCode(QUIC_NETWORK_IDLE_TIMEOUT);
 }

 TEST_P(QuicConnectionTest, TimeoutAfterReceive) {
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
   EXPECT_TRUE(connection_.connected());
   EXPECT_CALL(*send_algorithm_, SetFromConfig(_, _));
   QuicConfig config;
   connection_.SetFromConfig(config);
   EXPECT_FALSE(QuicConnectionPeer::IsSilentCloseEnabled(&connection_));

   const QuicTime::Delta initial_idle_timeout =
       QuicTime::Delta::FromSeconds(kInitialIdleTimeoutSecs - 1);
   const QuicTime::Delta five_ms = QuicTime::Delta::FromMilliseconds(5);
   QuicTime default_timeout = clock_.ApproximateNow() + initial_idle_timeout;

   connection_.SendStreamDataWithString(
       GetNthClientInitiatedStreamId(1, connection_.transport_version()), "foo",
       0, NO_FIN);
   connection_.SendStreamDataWithString(
       GetNthClientInitiatedStreamId(1, connection_.transport_version()), "foo",
       3, NO_FIN);

   EXPECT_EQ(default_timeout, connection_.GetTimeoutAlarm()->deadline());
   clock_.AdvanceTime(five_ms);

   // When we receive a packet, the timeout will change to 5ms +
   // kInitialIdleTimeoutSecs.
   QuicAckFrame ack = InitAckFrame(2);
   EXPECT_CALL(*send_algorithm_, OnCongestionEvent(true, _, _, _, _));
   ProcessAckPacket(&ack);

   // The original alarm will fire.  We should not time out because we had a
   // network event at t=5ms.  The alarm will reregister.
   clock_.AdvanceTime(initial_idle_timeout - five_ms);
   EXPECT_EQ(default_timeout, clock_.ApproximateNow());
   connection_.GetTimeoutAlarm()->Fire();
   EXPECT_TRUE(connection_.connected());
   EXPECT_TRUE(connection_.GetTimeoutAlarm()->IsSet());
   EXPECT_EQ(default_timeout + five_ms,
             connection_.GetTimeoutAlarm()->deadline());

   // This time, we should time out.
   EXPECT_CALL(visitor_,
               OnConnectionClosed(_, ConnectionCloseSource::FROM_SELF));
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(AtLeast(1));
   clock_.AdvanceTime(five_ms);
   EXPECT_EQ(default_timeout + five_ms, clock_.ApproximateNow());
   connection_.GetTimeoutAlarm()->Fire();
   EXPECT_FALSE(connection_.GetTimeoutAlarm()->IsSet());
   EXPECT_FALSE(connection_.connected());
   TestConnectionCloseQuicErrorCode(QUIC_NETWORK_IDLE_TIMEOUT);
 }

 TEST_P(QuicConnectionTest, TimeoutAfterReceiveNotSendWhenUnacked) {
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
   EXPECT_TRUE(connection_.connected());
   EXPECT_CALL(*send_algorithm_, SetFromConfig(_, _));
   QuicConfig config;
   connection_.SetFromConfig(config);
   EXPECT_FALSE(QuicConnectionPeer::IsSilentCloseEnabled(&connection_));

   const QuicTime::Delta initial_idle_timeout =
       QuicTime::Delta::FromSeconds(kInitialIdleTimeoutSecs - 1);
   connection_.SetNetworkTimeouts(
       QuicTime::Delta::Infinite(),
       initial_idle_timeout + QuicTime::Delta::FromSeconds(1));
   const QuicTime::Delta five_ms = QuicTime::Delta::FromMilliseconds(5);
   QuicTime default_timeout = clock_.ApproximateNow() + initial_idle_timeout;

   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _));
   connection_.SendStreamDataWithString(
       GetNthClientInitiatedStreamId(1, connection_.transport_version()), "foo",
       0, NO_FIN);
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _));
   connection_.SendStreamDataWithString(
       GetNthClientInitiatedStreamId(1, connection_.transport_version()), "foo",
       3, NO_FIN);

   EXPECT_EQ(default_timeout, connection_.GetTimeoutAlarm()->deadline());

   clock_.AdvanceTime(five_ms);

   // When we receive a packet, the timeout will change to 5ms +
   // kInitialIdleTimeoutSecs.
   QuicAckFrame ack = InitAckFrame(2);
   EXPECT_CALL(*send_algorithm_, OnCongestionEvent(true, _, _, _, _));
   ProcessAckPacket(&ack);

   // The original alarm will fire.  We should not time out because we had a
   // network event at t=5ms.  The alarm will reregister.
   clock_.AdvanceTime(initial_idle_timeout - five_ms);
   EXPECT_EQ(default_timeout, clock_.ApproximateNow());
   connection_.GetTimeoutAlarm()->Fire();
   EXPECT_TRUE(connection_.connected());
   EXPECT_TRUE(connection_.GetTimeoutAlarm()->IsSet());
   EXPECT_EQ(default_timeout + five_ms,
             connection_.GetTimeoutAlarm()->deadline());

   // Now, send packets while advancing the time and verify that the connection
   // eventually times out.
   EXPECT_CALL(visitor_,
               OnConnectionClosed(_, ConnectionCloseSource::FROM_SELF));
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(AnyNumber());
   for (int i = 0; i < 100 && connection_.connected(); ++i) {
     QUIC_LOG(INFO) << "sending data packet";
     connection_.SendStreamDataWithString(
         GetNthClientInitiatedStreamId(1, connection_.transport_version()),
         "foo", 0, NO_FIN);
     connection_.GetTimeoutAlarm()->Fire();
     clock_.AdvanceTime(QuicTime::Delta::FromSeconds(1));
   }
   EXPECT_FALSE(connection_.connected());
   EXPECT_FALSE(connection_.GetTimeoutAlarm()->IsSet());
   TestConnectionCloseQuicErrorCode(QUIC_NETWORK_IDLE_TIMEOUT);
 }

 TEST_P(QuicConnectionTest, TimeoutAfter5ClientRTOs) {
   if (connection_.PtoEnabled()) {
     return;
   }
   connection_.SetMaxTailLossProbes(2);
   EXPECT_TRUE(connection_.connected());
   EXPECT_CALL(*send_algorithm_, SetFromConfig(_, _));
   QuicConfig config;
   QuicTagVector connection_options;
   connection_options.push_back(k5RTO);
   config.SetConnectionOptionsToSend(connection_options);
   connection_.SetFromConfig(config);

   // Send stream data.
   SendStreamDataToPeer(
       GetNthClientInitiatedStreamId(1, connection_.transport_version()), "foo",
       0, FIN, nullptr);

   // Fire the retransmission alarm 6 times, twice for TLP and 4 times for RTO.
   for (int i = 0; i < 6; ++i) {
     EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _));
     connection_.GetRetransmissionAlarm()->Fire();
     EXPECT_TRUE(connection_.GetTimeoutAlarm()->IsSet());
     EXPECT_TRUE(connection_.connected());
   }

   EXPECT_EQ(2u, connection_.sent_packet_manager().GetConsecutiveTlpCount());
   EXPECT_EQ(4u, connection_.sent_packet_manager().GetConsecutiveRtoCount());
   // This time, we should time out.
   EXPECT_CALL(visitor_,
               OnConnectionClosed(_, ConnectionCloseSource::FROM_SELF));
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(AtLeast(1));
   connection_.GetRetransmissionAlarm()->Fire();
   EXPECT_FALSE(connection_.GetTimeoutAlarm()->IsSet());
   EXPECT_FALSE(connection_.connected());
   TestConnectionCloseQuicErrorCode(QUIC_TOO_MANY_RTOS);
 }

 TEST_P(QuicConnectionTest, SendScheduler) {
   // Test that if we send a packet without delay, it is not queued.
   QuicFramerPeer::SetPerspective(&peer_framer_, Perspective::IS_CLIENT);
   std::unique_ptr<QuicPacket> packet =
       ConstructDataPacket(1, !kHasStopWaiting, ENCRYPTION_INITIAL);
   QuicPacketCreatorPeer::SetPacketNumber(creator_, 1);
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _));
   connection_.SendPacket(ENCRYPTION_INITIAL, 1, std::move(packet),
                          HAS_RETRANSMITTABLE_DATA, false, false);
   EXPECT_EQ(0u, connection_.NumQueuedPackets());
 }

 TEST_P(QuicConnectionTest, FailToSendFirstPacket) {
   // Test that the connection does not crash when it fails to send the first
   // packet at which point self_address_ might be uninitialized.
   QuicFramerPeer::SetPerspective(&peer_framer_, Perspective::IS_CLIENT);
   EXPECT_CALL(visitor_, OnConnectionClosed(_, _)).Times(1);
   std::unique_ptr<QuicPacket> packet =
       ConstructDataPacket(1, !kHasStopWaiting, ENCRYPTION_INITIAL);
   QuicPacketCreatorPeer::SetPacketNumber(creator_, 1);
   writer_->SetShouldWriteFail();
   connection_.SendPacket(ENCRYPTION_INITIAL, 1, std::move(packet),
                          HAS_RETRANSMITTABLE_DATA, false, false);
 }

 TEST_P(QuicConnectionTest, SendSchedulerEAGAIN) {
   QuicFramerPeer::SetPerspective(&peer_framer_, Perspective::IS_CLIENT);
   std::unique_ptr<QuicPacket> packet =
       ConstructDataPacket(1, !kHasStopWaiting, ENCRYPTION_INITIAL);
   QuicPacketCreatorPeer::SetPacketNumber(creator_, 1);
   BlockOnNextWrite();
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, QuicPacketNumber(2u), _, _))
       .Times(0);
   connection_.SendPacket(ENCRYPTION_INITIAL, 1, std::move(packet),
                          HAS_RETRANSMITTABLE_DATA, false, false);
   EXPECT_EQ(1u, connection_.NumQueuedPackets());
 }

 TEST_P(QuicConnectionTest, TestQueueLimitsOnSendStreamData) {
   // Queue the first packet.
   size_t payload_length = connection_.max_packet_length();
   EXPECT_CALL(*send_algorithm_, CanSend(_)).WillOnce(testing::Return(false));
   const std::string payload(payload_length, 'a');
   QuicStreamId first_bidi_stream_id(QuicUtils::GetFirstBidirectionalStreamId(
       connection_.version().transport_version, Perspective::IS_CLIENT));
   EXPECT_EQ(0u, connection_
                     .SendStreamDataWithString(first_bidi_stream_id, payload, 0,
                                               NO_FIN)
                     .bytes_consumed);
   EXPECT_EQ(0u, connection_.NumQueuedPackets());
 }

 TEST_P(QuicConnectionTest, SendingThreePackets) {
   // Make the payload twice the size of the packet, so 3 packets are written.
   size_t total_payload_length = 2 * connection_.max_packet_length();
   const std::string payload(total_payload_length, 'a');
   QuicStreamId first_bidi_stream_id(QuicUtils::GetFirstBidirectionalStreamId(
       connection_.version().transport_version, Perspective::IS_CLIENT));
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(3);
   EXPECT_EQ(payload.size(), connection_
                                 .SendStreamDataWithString(first_bidi_stream_id,
                                                           payload, 0, NO_FIN)
                                 .bytes_consumed);
 }

 TEST_P(QuicConnectionTest, LoopThroughSendingPacketsWithTruncation) {
   set_perspective(Perspective::IS_SERVER);
   if (!VersionHasIetfInvariantHeader(GetParam().version.transport_version)) {
     // For IETF QUIC, encryption level will be switched to FORWARD_SECURE in
     // SendStreamDataWithString.
     QuicPacketCreatorPeer::SetSendVersionInPacket(creator_, false);
   }
   // Set up a larger payload than will fit in one packet.
   const std::string payload(connection_.max_packet_length(), 'a');
   EXPECT_CALL(*send_algorithm_, SetFromConfig(_, _)).Times(AnyNumber());

   // Now send some packets with no truncation.
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(2);
   EXPECT_EQ(payload.size(),
             connection_.SendStreamDataWithString(3, payload, 0, NO_FIN)
                 .bytes_consumed);
   // Track the size of the second packet here.  The overhead will be the largest
   // we see in this test, due to the non-truncated connection id.
   size_t non_truncated_packet_size = writer_->last_packet_size();

   // Change to a 0 byte connection id.
   QuicConfig config;
   QuicConfigPeer::SetReceivedBytesForConnectionId(&config, 0);
   connection_.SetFromConfig(config);
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(2);
   EXPECT_EQ(payload.size(),
             connection_.SendStreamDataWithString(3, payload, 1350, NO_FIN)
                 .bytes_consumed);
   if (VersionHasIetfInvariantHeader(connection_.transport_version())) {
     // Short header packets sent from server omit connection ID already, and
     // stream offset size increases from 0 to 2.
     EXPECT_EQ(non_truncated_packet_size, writer_->last_packet_size() - 2);
   } else {
     // Just like above, we save 8 bytes on payload, and 8 on truncation. -2
     // because stream offset size is 2 instead of 0.
     EXPECT_EQ(non_truncated_packet_size,
               writer_->last_packet_size() + 8 * 2 - 2);
   }
 }

 TEST_P(QuicConnectionTest, SendDelayedAck) {
   QuicTime ack_time = clock_.ApproximateNow() + DefaultDelayedAckTime();
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
   EXPECT_FALSE(connection_.GetAckAlarm()->IsSet());
   const uint8_t tag = 0x07;
   SetDecrypter(ENCRYPTION_ZERO_RTT,
                std::make_unique<StrictTaggingDecrypter>(tag));
   peer_framer_.SetEncrypter(ENCRYPTION_ZERO_RTT,
                             std::make_unique<TaggingEncrypter>(tag));
   // Process a packet from the non-crypto stream.
   frame1_.stream_id = 3;

   // The same as ProcessPacket(1) except that ENCRYPTION_ZERO_RTT is used
   // instead of ENCRYPTION_INITIAL.
   EXPECT_CALL(visitor_, OnStreamFrame(_)).Times(1);
   ProcessDataPacketAtLevel(1, !kHasStopWaiting, ENCRYPTION_ZERO_RTT);

   // Check if delayed ack timer is running for the expected interval.
   EXPECT_TRUE(connection_.GetAckAlarm()->IsSet());
   EXPECT_EQ(ack_time, connection_.GetAckAlarm()->deadline());
   // Simulate delayed ack alarm firing.
   clock_.AdvanceTime(DefaultDelayedAckTime());
   connection_.GetAckAlarm()->Fire();
   // Check that ack is sent and that delayed ack alarm is reset.
   size_t padding_frame_count = writer_->padding_frames().size();
   if (GetParam().no_stop_waiting) {
     EXPECT_EQ(padding_frame_count + 1u, writer_->frame_count());
     EXPECT_TRUE(writer_->stop_waiting_frames().empty());
   } else {
     EXPECT_EQ(padding_frame_count + 2u, writer_->frame_count());
     EXPECT_FALSE(writer_->stop_waiting_frames().empty());
   }
   EXPECT_FALSE(writer_->ack_frames().empty());
   EXPECT_FALSE(connection_.GetAckAlarm()->IsSet());
 }

 TEST_P(QuicConnectionTest, SendDelayedAfterQuiescence) {
   QuicConnectionPeer::SetFastAckAfterQuiescence(&connection_, true);

   // The beginning of the connection counts as quiescence.
   QuicTime ack_time =
       clock_.ApproximateNow() + QuicTime::Delta::FromMilliseconds(1);
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
   EXPECT_FALSE(connection_.GetAckAlarm()->IsSet());
   const uint8_t tag = 0x07;
   SetDecrypter(ENCRYPTION_ZERO_RTT,
                std::make_unique<StrictTaggingDecrypter>(tag));
   peer_framer_.SetEncrypter(ENCRYPTION_ZERO_RTT,
                             std::make_unique<TaggingEncrypter>(tag));
   // Process a packet from the non-crypto stream.
   frame1_.stream_id = 3;

   // The same as ProcessPacket(1) except that ENCRYPTION_ZERO_RTT is used
   // instead of ENCRYPTION_INITIAL.
   EXPECT_CALL(visitor_, OnStreamFrame(_)).Times(1);
   ProcessDataPacketAtLevel(1, !kHasStopWaiting, ENCRYPTION_ZERO_RTT);

   // Check if delayed ack timer is running for the expected interval.
   EXPECT_TRUE(connection_.GetAckAlarm()->IsSet());
   EXPECT_EQ(ack_time, connection_.GetAckAlarm()->deadline());
   // Simulate delayed ack alarm firing.
   clock_.AdvanceTime(DefaultDelayedAckTime());
   connection_.GetAckAlarm()->Fire();
   // Check that ack is sent and that delayed ack alarm is reset.
   size_t padding_frame_count = writer_->padding_frames().size();
   if (GetParam().no_stop_waiting) {
     EXPECT_EQ(padding_frame_count + 1u, writer_->frame_count());
     EXPECT_TRUE(writer_->stop_waiting_frames().empty());
   } else {
     EXPECT_EQ(padding_frame_count + 2u, writer_->frame_count());
     EXPECT_FALSE(writer_->stop_waiting_frames().empty());
   }
   EXPECT_FALSE(writer_->ack_frames().empty());
   EXPECT_FALSE(connection_.GetAckAlarm()->IsSet());

   // Process another packet immedately after sending the ack and expect the
   // ack alarm to be set delayed ack time in the future.
   ack_time = clock_.ApproximateNow() + DefaultDelayedAckTime();
   EXPECT_CALL(visitor_, OnStreamFrame(_)).Times(1);
   ProcessDataPacketAtLevel(2, !kHasStopWaiting, ENCRYPTION_ZERO_RTT);

   // Check if delayed ack timer is running for the expected interval.
   EXPECT_TRUE(connection_.GetAckAlarm()->IsSet());
   EXPECT_EQ(ack_time, connection_.GetAckAlarm()->deadline());
   // Simulate delayed ack alarm firing.
   clock_.AdvanceTime(DefaultDelayedAckTime());
   connection_.GetAckAlarm()->Fire();
   // Check that ack is sent and that delayed ack alarm is reset.
   padding_frame_count = writer_->padding_frames().size();
   if (GetParam().no_stop_waiting) {
     EXPECT_EQ(padding_frame_count + 1u, writer_->frame_count());
     EXPECT_TRUE(writer_->stop_waiting_frames().empty());
   } else {
     EXPECT_EQ(padding_frame_count + 2u, writer_->frame_count());
     EXPECT_FALSE(writer_->stop_waiting_frames().empty());
   }
   EXPECT_FALSE(writer_->ack_frames().empty());
   EXPECT_FALSE(connection_.GetAckAlarm()->IsSet());

   // Wait 1 second and enesure the ack alarm is set to 1ms in the future.
   clock_.AdvanceTime(QuicTime::Delta::FromSeconds(1));
   ack_time = clock_.ApproximateNow() + QuicTime::Delta::FromMilliseconds(1);
   EXPECT_CALL(visitor_, OnStreamFrame(_)).Times(1);
   ProcessDataPacketAtLevel(3, !kHasStopWaiting, ENCRYPTION_ZERO_RTT);

   // Check if delayed ack timer is running for the expected interval.
   EXPECT_TRUE(connection_.GetAckAlarm()->IsSet());
   EXPECT_EQ(ack_time, connection_.GetAckAlarm()->deadline());
 }

 TEST_P(QuicConnectionTest, SendDelayedAckDecimation) {
   EXPECT_CALL(visitor_, OnAckNeedsRetransmittableFrame()).Times(AnyNumber());
   QuicConnectionPeer::SetAckMode(&connection_, ACK_DECIMATION);

   const size_t kMinRttMs = 40;
   RttStats* rtt_stats = const_cast<RttStats*>(manager_->GetRttStats());
   rtt_stats->UpdateRtt(QuicTime::Delta::FromMilliseconds(kMinRttMs),
                        QuicTime::Delta::Zero(), QuicTime::Zero());
   // The ack time should be based on min_rtt/4, since it's less than the
   // default delayed ack time.
   QuicTime ack_time = clock_.ApproximateNow() +
                       QuicTime::Delta::FromMilliseconds(kMinRttMs / 4);
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
   EXPECT_FALSE(connection_.GetAckAlarm()->IsSet());
   const uint8_t tag = 0x07;
   SetDecrypter(ENCRYPTION_ZERO_RTT,
                std::make_unique<StrictTaggingDecrypter>(tag));
   peer_framer_.SetEncrypter(ENCRYPTION_ZERO_RTT,
                             std::make_unique<TaggingEncrypter>(tag));
   // Process a packet from the non-crypto stream.
   frame1_.stream_id = 3;

   // Process all the initial packets in order so there aren't missing packets.
   uint64_t kFirstDecimatedPacket = 101;
   for (unsigned int i = 0; i < kFirstDecimatedPacket - 1; ++i) {
     EXPECT_CALL(visitor_, OnStreamFrame(_)).Times(1);
     ProcessDataPacketAtLevel(1 + i, !kHasStopWaiting, ENCRYPTION_ZERO_RTT);
   }
   EXPECT_FALSE(connection_.GetAckAlarm()->IsSet());
   // The same as ProcessPacket(1) except that ENCRYPTION_ZERO_RTT is used
   // instead of ENCRYPTION_INITIAL.
   EXPECT_CALL(visitor_, OnStreamFrame(_)).Times(1);
   ProcessDataPacketAtLevel(kFirstDecimatedPacket, !kHasStopWaiting,
                            ENCRYPTION_ZERO_RTT);

   // Check if delayed ack timer is running for the expected interval.
   EXPECT_TRUE(connection_.GetAckAlarm()->IsSet());
   EXPECT_EQ(ack_time, connection_.GetAckAlarm()->deadline());

   // The 10th received packet causes an ack to be sent.
   for (int i = 0; i < 9; ++i) {
     EXPECT_TRUE(connection_.GetAckAlarm()->IsSet());
     EXPECT_CALL(visitor_, OnStreamFrame(_)).Times(1);
     ProcessDataPacketAtLevel(kFirstDecimatedPacket + 1 + i, !kHasStopWaiting,
                              ENCRYPTION_ZERO_RTT);
   }
   // Check that ack is sent and that delayed ack alarm is reset.
   size_t padding_frame_count = writer_->padding_frames().size();
   if (GetParam().no_stop_waiting) {
     EXPECT_EQ(padding_frame_count + 1u, writer_->frame_count());
     EXPECT_TRUE(writer_->stop_waiting_frames().empty());
   } else {
     EXPECT_EQ(padding_frame_count + 2u, writer_->frame_count());
     EXPECT_FALSE(writer_->stop_waiting_frames().empty());
   }
   EXPECT_FALSE(writer_->ack_frames().empty());
   EXPECT_FALSE(connection_.GetAckAlarm()->IsSet());
 }

 TEST_P(QuicConnectionTest, SendDelayedAckAckDecimationAfterQuiescence) {
   EXPECT_CALL(visitor_, OnAckNeedsRetransmittableFrame()).Times(AnyNumber());
   QuicConnectionPeer::SetAckMode(&connection_, ACK_DECIMATION);
   QuicConnectionPeer::SetFastAckAfterQuiescence(&connection_, true);

   const size_t kMinRttMs = 40;
   RttStats* rtt_stats = const_cast<RttStats*>(manager_->GetRttStats());
   rtt_stats->UpdateRtt(QuicTime::Delta::FromMilliseconds(kMinRttMs),
                        QuicTime::Delta::Zero(), QuicTime::Zero());

   // The beginning of the connection counts as quiescence.
   QuicTime ack_time =
       clock_.ApproximateNow() + QuicTime::Delta::FromMilliseconds(1);
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
   EXPECT_FALSE(connection_.GetAckAlarm()->IsSet());
   const uint8_t tag = 0x07;
   SetDecrypter(ENCRYPTION_ZERO_RTT,
                std::make_unique<StrictTaggingDecrypter>(tag));
   peer_framer_.SetEncrypter(ENCRYPTION_ZERO_RTT,
                             std::make_unique<TaggingEncrypter>(tag));
   // Process a packet from the non-crypto stream.
   frame1_.stream_id = 3;

   // The same as ProcessPacket(1) except that ENCRYPTION_ZERO_RTT is used
   // instead of ENCRYPTION_INITIAL.
   EXPECT_CALL(visitor_, OnStreamFrame(_)).Times(1);
   ProcessDataPacketAtLevel(1, !kHasStopWaiting, ENCRYPTION_ZERO_RTT);

   // Check if delayed ack timer is running for the expected interval.
   EXPECT_TRUE(connection_.GetAckAlarm()->IsSet());
   EXPECT_EQ(ack_time, connection_.GetAckAlarm()->deadline());
   // Simulate delayed ack alarm firing.
   clock_.AdvanceTime(DefaultDelayedAckTime());
   connection_.GetAckAlarm()->Fire();
   // Check that ack is sent and that delayed ack alarm is reset.
   size_t padding_frame_count = writer_->padding_frames().size();
   if (GetParam().no_stop_waiting) {
     EXPECT_EQ(padding_frame_count + 1u, writer_->frame_count());
     EXPECT_TRUE(writer_->stop_waiting_frames().empty());
   } else {
     EXPECT_EQ(padding_frame_count + 2u, writer_->frame_count());
     EXPECT_FALSE(writer_->stop_waiting_frames().empty());
   }
   EXPECT_FALSE(writer_->ack_frames().empty());
   EXPECT_FALSE(connection_.GetAckAlarm()->IsSet());

   // Process another packet immedately after sending the ack and expect the
   // ack alarm to be set delayed ack time in the future.
   ack_time = clock_.ApproximateNow() + DefaultDelayedAckTime();
   EXPECT_CALL(visitor_, OnStreamFrame(_)).Times(1);
   ProcessDataPacketAtLevel(2, !kHasStopWaiting, ENCRYPTION_ZERO_RTT);

   // Check if delayed ack timer is running for the expected interval.
   EXPECT_TRUE(connection_.GetAckAlarm()->IsSet());
   EXPECT_EQ(ack_time, connection_.GetAckAlarm()->deadline());
   // Simulate delayed ack alarm firing.
   clock_.AdvanceTime(DefaultDelayedAckTime());
   connection_.GetAckAlarm()->Fire();
   // Check that ack is sent and that delayed ack alarm is reset.
   padding_frame_count = writer_->padding_frames().size();
   if (GetParam().no_stop_waiting) {
     EXPECT_EQ(padding_frame_count + 1u, writer_->frame_count());
     EXPECT_TRUE(writer_->stop_waiting_frames().empty());
   } else {
     EXPECT_EQ(padding_frame_count + 2u, writer_->frame_count());
     EXPECT_FALSE(writer_->stop_waiting_frames().empty());
   }
   EXPECT_FALSE(writer_->ack_frames().empty());
   EXPECT_FALSE(connection_.GetAckAlarm()->IsSet());

   // Wait 1 second and enesure the ack alarm is set to 1ms in the future.
   clock_.AdvanceTime(QuicTime::Delta::FromSeconds(1));
   ack_time = clock_.ApproximateNow() + QuicTime::Delta::FromMilliseconds(1);
   EXPECT_CALL(visitor_, OnStreamFrame(_)).Times(1);
   ProcessDataPacketAtLevel(3, !kHasStopWaiting, ENCRYPTION_ZERO_RTT);

   // Check if delayed ack timer is running for the expected interval.
   EXPECT_TRUE(connection_.GetAckAlarm()->IsSet());
   EXPECT_EQ(ack_time, connection_.GetAckAlarm()->deadline());

   // Process enough packets to get into ack decimation behavior.
   // The ack time should be based on min_rtt/4, since it's less than the
   // default delayed ack time.
   ack_time = clock_.ApproximateNow() +
              QuicTime::Delta::FromMilliseconds(kMinRttMs / 4);
   uint64_t kFirstDecimatedPacket = 101;
   for (unsigned int i = 0; i < kFirstDecimatedPacket - 4; ++i) {
     EXPECT_CALL(visitor_, OnStreamFrame(_)).Times(1);
     ProcessDataPacketAtLevel(4 + i, !kHasStopWaiting, ENCRYPTION_ZERO_RTT);
   }
   EXPECT_FALSE(connection_.GetAckAlarm()->IsSet());
   // The same as ProcessPacket(1) except that ENCRYPTION_ZERO_RTT is used
   // instead of ENCRYPTION_INITIAL.
   EXPECT_CALL(visitor_, OnStreamFrame(_)).Times(1);
   ProcessDataPacketAtLevel(kFirstDecimatedPacket, !kHasStopWaiting,
                            ENCRYPTION_ZERO_RTT);

   // Check if delayed ack timer is running for the expected interval.
   EXPECT_TRUE(connection_.GetAckAlarm()->IsSet());
   EXPECT_EQ(ack_time, connection_.GetAckAlarm()->deadline());

   // The 10th received packet causes an ack to be sent.
   for (int i = 0; i < 9; ++i) {
     EXPECT_TRUE(connection_.GetAckAlarm()->IsSet());
     EXPECT_CALL(visitor_, OnStreamFrame(_)).Times(1);
     ProcessDataPacketAtLevel(kFirstDecimatedPacket + 1 + i, !kHasStopWaiting,
                              ENCRYPTION_ZERO_RTT);
   }
   // Check that ack is sent and that delayed ack alarm is reset.
   padding_frame_count = writer_->padding_frames().size();
   if (GetParam().no_stop_waiting) {
     EXPECT_EQ(padding_frame_count + 1u, writer_->frame_count());
     EXPECT_TRUE(writer_->stop_waiting_frames().empty());
   } else {
     EXPECT_EQ(padding_frame_count + 2u, writer_->frame_count());
     EXPECT_FALSE(writer_->stop_waiting_frames().empty());
   }
   EXPECT_FALSE(writer_->ack_frames().empty());
   EXPECT_FALSE(connection_.GetAckAlarm()->IsSet());

   // Wait 1 second and enesure the ack alarm is set to 1ms in the future.
   clock_.AdvanceTime(QuicTime::Delta::FromSeconds(1));
   ack_time = clock_.ApproximateNow() + QuicTime::Delta::FromMilliseconds(1);
   EXPECT_CALL(visitor_, OnStreamFrame(_)).Times(1);
   ProcessDataPacketAtLevel(kFirstDecimatedPacket + 10, !kHasStopWaiting,
                            ENCRYPTION_ZERO_RTT);

   // Check if delayed ack timer is running for the expected interval.
   EXPECT_TRUE(connection_.GetAckAlarm()->IsSet());
   EXPECT_EQ(ack_time, connection_.GetAckAlarm()->deadline());
 }

 TEST_P(QuicConnectionTest, SendDelayedAckDecimationUnlimitedAggregation) {
   EXPECT_CALL(visitor_, OnAckNeedsRetransmittableFrame()).Times(AnyNumber());
   EXPECT_CALL(*send_algorithm_, SetFromConfig(_, _));
   QuicConfig config;
   QuicTagVector connection_options;
   connection_options.push_back(kACKD);
   // No limit on the number of packets received before sending an ack.
   connection_options.push_back(kAKDU);
   config.SetConnectionOptionsToSend(connection_options);
   connection_.SetFromConfig(config);

   const size_t kMinRttMs = 40;
   RttStats* rtt_stats = const_cast<RttStats*>(manager_->GetRttStats());
   rtt_stats->UpdateRtt(QuicTime::Delta::FromMilliseconds(kMinRttMs),
                        QuicTime::Delta::Zero(), QuicTime::Zero());
   // The ack time should be based on min_rtt/4, since it's less than the
   // default delayed ack time.
   QuicTime ack_time = clock_.ApproximateNow() +
                       QuicTime::Delta::FromMilliseconds(kMinRttMs / 4);
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
   EXPECT_FALSE(connection_.GetAckAlarm()->IsSet());
   const uint8_t tag = 0x07;
   SetDecrypter(ENCRYPTION_ZERO_RTT,
                std::make_unique<StrictTaggingDecrypter>(tag));
   peer_framer_.SetEncrypter(ENCRYPTION_ZERO_RTT,
                             std::make_unique<TaggingEncrypter>(tag));
   // Process a packet from the non-crypto stream.
   frame1_.stream_id = 3;

   // Process all the initial packets in order so there aren't missing packets.
   uint64_t kFirstDecimatedPacket = 101;
   for (unsigned int i = 0; i < kFirstDecimatedPacket - 1; ++i) {
     EXPECT_CALL(visitor_, OnStreamFrame(_)).Times(1);
     ProcessDataPacketAtLevel(1 + i, !kHasStopWaiting, ENCRYPTION_ZERO_RTT);
   }
   EXPECT_FALSE(connection_.GetAckAlarm()->IsSet());
   // The same as ProcessPacket(1) except that ENCRYPTION_ZERO_RTT is used
   // instead of ENCRYPTION_INITIAL.
   EXPECT_CALL(visitor_, OnStreamFrame(_)).Times(1);
   ProcessDataPacketAtLevel(kFirstDecimatedPacket, !kHasStopWaiting,
                            ENCRYPTION_ZERO_RTT);

   // Check if delayed ack timer is running for the expected interval.
   EXPECT_TRUE(connection_.GetAckAlarm()->IsSet());
   EXPECT_EQ(ack_time, connection_.GetAckAlarm()->deadline());

   // 18 packets will not cause an ack to be sent.  19 will because when
   // stop waiting frames are in use, we ack every 20 packets no matter what.
   for (int i = 0; i < 18; ++i) {
     EXPECT_TRUE(connection_.GetAckAlarm()->IsSet());
     EXPECT_CALL(visitor_, OnStreamFrame(_)).Times(1);
     ProcessDataPacketAtLevel(kFirstDecimatedPacket + 1 + i, !kHasStopWaiting,
                              ENCRYPTION_ZERO_RTT);
   }
   // The delayed ack timer should still be set to the expected deadline.
   EXPECT_TRUE(connection_.GetAckAlarm()->IsSet());
   EXPECT_EQ(ack_time, connection_.GetAckAlarm()->deadline());
 }

 TEST_P(QuicConnectionTest, SendDelayedAckDecimationEighthRtt) {
   EXPECT_CALL(visitor_, OnAckNeedsRetransmittableFrame()).Times(AnyNumber());
   QuicConnectionPeer::SetAckMode(&connection_, ACK_DECIMATION);
   QuicConnectionPeer::SetAckDecimationDelay(&connection_, 0.125);

   const size_t kMinRttMs = 40;
   RttStats* rtt_stats = const_cast<RttStats*>(manager_->GetRttStats());
   rtt_stats->UpdateRtt(QuicTime::Delta::FromMilliseconds(kMinRttMs),
                        QuicTime::Delta::Zero(), QuicTime::Zero());
   // The ack time should be based on min_rtt/8, since it's less than the
   // default delayed ack time.
   QuicTime ack_time = clock_.ApproximateNow() +
                       QuicTime::Delta::FromMilliseconds(kMinRttMs / 8);
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
   EXPECT_FALSE(connection_.GetAckAlarm()->IsSet());
   const uint8_t tag = 0x07;
   SetDecrypter(ENCRYPTION_ZERO_RTT,
                std::make_unique<StrictTaggingDecrypter>(tag));
   peer_framer_.SetEncrypter(ENCRYPTION_ZERO_RTT,
                             std::make_unique<TaggingEncrypter>(tag));
   // Process a packet from the non-crypto stream.
   frame1_.stream_id = 3;

   // Process all the initial packets in order so there aren't missing packets.
   uint64_t kFirstDecimatedPacket = 101;
   for (unsigned int i = 0; i < kFirstDecimatedPacket - 1; ++i) {
     EXPECT_CALL(visitor_, OnStreamFrame(_)).Times(1);
     ProcessDataPacketAtLevel(1 + i, !kHasStopWaiting, ENCRYPTION_ZERO_RTT);
   }
   EXPECT_FALSE(connection_.GetAckAlarm()->IsSet());
   // The same as ProcessPacket(1) except that ENCRYPTION_ZERO_RTT is used
   // instead of ENCRYPTION_INITIAL.
   EXPECT_CALL(visitor_, OnStreamFrame(_)).Times(1);
   ProcessDataPacketAtLevel(kFirstDecimatedPacket, !kHasStopWaiting,
                            ENCRYPTION_ZERO_RTT);

   // Check if delayed ack timer is running for the expected interval.
   EXPECT_TRUE(connection_.GetAckAlarm()->IsSet());
   EXPECT_EQ(ack_time, connection_.GetAckAlarm()->deadline());

   // The 10th received packet causes an ack to be sent.
   for (int i = 0; i < 9; ++i) {
     EXPECT_TRUE(connection_.GetAckAlarm()->IsSet());
     EXPECT_CALL(visitor_, OnStreamFrame(_)).Times(1);
     ProcessDataPacketAtLevel(kFirstDecimatedPacket + 1 + i, !kHasStopWaiting,
                              ENCRYPTION_ZERO_RTT);
   }
   // Check that ack is sent and that delayed ack alarm is reset.
   size_t padding_frame_count = writer_->padding_frames().size();
   if (GetParam().no_stop_waiting) {
     EXPECT_EQ(padding_frame_count + 1u, writer_->frame_count());
     EXPECT_TRUE(writer_->stop_waiting_frames().empty());
   } else {
     EXPECT_EQ(padding_frame_count + 2u, writer_->frame_count());
     EXPECT_FALSE(writer_->stop_waiting_frames().empty());
   }
   EXPECT_FALSE(writer_->ack_frames().empty());
   EXPECT_FALSE(connection_.GetAckAlarm()->IsSet());
 }

 TEST_P(QuicConnectionTest, SendDelayedAckDecimationWithReordering) {
   EXPECT_CALL(visitor_, OnAckNeedsRetransmittableFrame()).Times(AnyNumber());
   QuicConnectionPeer::SetAckMode(&connection_, ACK_DECIMATION_WITH_REORDERING);

   const size_t kMinRttMs = 40;
   RttStats* rtt_stats = const_cast<RttStats*>(manager_->GetRttStats());
   rtt_stats->UpdateRtt(QuicTime::Delta::FromMilliseconds(kMinRttMs),
                        QuicTime::Delta::Zero(), QuicTime::Zero());
   // The ack time should be based on min_rtt/4, since it's less than the
   // default delayed ack time.
   QuicTime ack_time = clock_.ApproximateNow() +
                       QuicTime::Delta::FromMilliseconds(kMinRttMs / 4);
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
   EXPECT_FALSE(connection_.GetAckAlarm()->IsSet());
   const uint8_t tag = 0x07;
   SetDecrypter(ENCRYPTION_ZERO_RTT,
                std::make_unique<StrictTaggingDecrypter>(tag));
   peer_framer_.SetEncrypter(ENCRYPTION_ZERO_RTT,
                             std::make_unique<TaggingEncrypter>(tag));
   // Process a packet from the non-crypto stream.
   frame1_.stream_id = 3;

   // Process all the initial packets in order so there aren't missing packets.
   uint64_t kFirstDecimatedPacket = 101;
   for (unsigned int i = 0; i < kFirstDecimatedPacket - 1; ++i) {
     EXPECT_CALL(visitor_, OnStreamFrame(_)).Times(1);
     ProcessDataPacketAtLevel(1 + i, !kHasStopWaiting, ENCRYPTION_ZERO_RTT);
   }
   EXPECT_FALSE(connection_.GetAckAlarm()->IsSet());

   // Receive one packet out of order and then the rest in order.
   // The loop leaves a one packet gap between acks sent to simulate some loss.
   for (int j = 0; j < 3; ++j) {
     // Process packet 10 first and ensure the alarm is one eighth min_rtt.
     EXPECT_CALL(visitor_, OnStreamFrame(_)).Times(1);
     ProcessDataPacketAtLevel(kFirstDecimatedPacket + 9 + (j * 11),
                              !kHasStopWaiting, ENCRYPTION_ZERO_RTT);
     ack_time = clock_.ApproximateNow() + QuicTime::Delta::FromMilliseconds(5);
     EXPECT_TRUE(connection_.GetAckAlarm()->IsSet());
     EXPECT_EQ(ack_time, connection_.GetAckAlarm()->deadline());

     // The 10th received packet causes an ack to be sent.
     writer_->Reset();
     for (int i = 0; i < 9; ++i) {
       EXPECT_TRUE(connection_.GetAckAlarm()->IsSet());
       EXPECT_CALL(visitor_, OnStreamFrame(_)).Times(1);
       // The ACK shouldn't be sent until the 10th packet is processed.
       EXPECT_TRUE(writer_->ack_frames().empty());
       ProcessDataPacketAtLevel(kFirstDecimatedPacket + i + (j * 11),
                                !kHasStopWaiting, ENCRYPTION_ZERO_RTT);
     }
     // Check that ack is sent and that delayed ack alarm is reset.
     size_t padding_frame_count = writer_->padding_frames().size();
     if (GetParam().no_stop_waiting) {
       EXPECT_EQ(padding_frame_count + 1u, writer_->frame_count());
       EXPECT_TRUE(writer_->stop_waiting_frames().empty());
     } else {
       EXPECT_EQ(padding_frame_count + 2u, writer_->frame_count());
       EXPECT_FALSE(writer_->stop_waiting_frames().empty());
     }
     EXPECT_FALSE(writer_->ack_frames().empty());
     EXPECT_FALSE(connection_.GetAckAlarm()->IsSet());
   }
 }

 TEST_P(QuicConnectionTest, SendDelayedAckDecimationWithLargeReordering) {
   EXPECT_CALL(visitor_, OnAckNeedsRetransmittableFrame()).Times(AnyNumber());
   QuicConnectionPeer::SetAckMode(&connection_, ACK_DECIMATION_WITH_REORDERING);

   const size_t kMinRttMs = 40;
   RttStats* rtt_stats = const_cast<RttStats*>(manager_->GetRttStats());
   rtt_stats->UpdateRtt(QuicTime::Delta::FromMilliseconds(kMinRttMs),
                        QuicTime::Delta::Zero(), QuicTime::Zero());
   // The ack time should be based on min_rtt/4, since it's less than the
   // default delayed ack time.
   QuicTime ack_time = clock_.ApproximateNow() +
                       QuicTime::Delta::FromMilliseconds(kMinRttMs / 4);
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
   EXPECT_FALSE(connection_.GetAckAlarm()->IsSet());
   const uint8_t tag = 0x07;
   SetDecrypter(ENCRYPTION_ZERO_RTT,
                std::make_unique<StrictTaggingDecrypter>(tag));
   peer_framer_.SetEncrypter(ENCRYPTION_ZERO_RTT,
                             std::make_unique<TaggingEncrypter>(tag));
   // Process a packet from the non-crypto stream.
   frame1_.stream_id = 3;

   // Process all the initial packets in order so there aren't missing packets.
   uint64_t kFirstDecimatedPacket = 101;
   for (unsigned int i = 0; i < kFirstDecimatedPacket - 1; ++i) {
     EXPECT_CALL(visitor_, OnStreamFrame(_)).Times(1);
     ProcessDataPacketAtLevel(1 + i, !kHasStopWaiting, ENCRYPTION_ZERO_RTT);
   }
   EXPECT_FALSE(connection_.GetAckAlarm()->IsSet());
   // The same as ProcessPacket(1) except that ENCRYPTION_ZERO_RTT is used
   // instead of ENCRYPTION_INITIAL.
   EXPECT_CALL(visitor_, OnStreamFrame(_)).Times(1);
   ProcessDataPacketAtLevel(kFirstDecimatedPacket, !kHasStopWaiting,
                            ENCRYPTION_ZERO_RTT);

   // Check if delayed ack timer is running for the expected interval.
   EXPECT_TRUE(connection_.GetAckAlarm()->IsSet());
   EXPECT_EQ(ack_time, connection_.GetAckAlarm()->deadline());

   // Process packet 10 first and ensure the alarm is one eighth min_rtt.
   EXPECT_CALL(visitor_, OnStreamFrame(_)).Times(1);
   ProcessDataPacketAtLevel(kFirstDecimatedPacket + 19, !kHasStopWaiting,
                            ENCRYPTION_ZERO_RTT);
   ack_time = clock_.ApproximateNow() + QuicTime::Delta::FromMilliseconds(5);
   EXPECT_TRUE(connection_.GetAckAlarm()->IsSet());
   EXPECT_EQ(ack_time, connection_.GetAckAlarm()->deadline());

   // The 10th received packet causes an ack to be sent.
   for (int i = 0; i < 8; ++i) {
     EXPECT_TRUE(connection_.GetAckAlarm()->IsSet());
     EXPECT_CALL(visitor_, OnStreamFrame(_)).Times(1);
     ProcessDataPacketAtLevel(kFirstDecimatedPacket + 1 + i, !kHasStopWaiting,
                              ENCRYPTION_ZERO_RTT);
   }
   // Check that ack is sent and that delayed ack alarm is reset.
   if (GetParam().no_stop_waiting) {
     EXPECT_EQ(1u, writer_->frame_count());
     EXPECT_TRUE(writer_->stop_waiting_frames().empty());
   } else {
     EXPECT_EQ(2u, writer_->frame_count());
     EXPECT_FALSE(writer_->stop_waiting_frames().empty());
   }
   EXPECT_FALSE(writer_->ack_frames().empty());
   EXPECT_FALSE(connection_.GetAckAlarm()->IsSet());

   // The next packet received in order will cause an immediate ack,
   // because it fills a hole.
   EXPECT_FALSE(connection_.GetAckAlarm()->IsSet());
   EXPECT_CALL(visitor_, OnStreamFrame(_)).Times(1);
   ProcessDataPacketAtLevel(kFirstDecimatedPacket + 10, !kHasStopWaiting,
                            ENCRYPTION_ZERO_RTT);
   // Check that ack is sent and that delayed ack alarm is reset.
   if (GetParam().no_stop_waiting) {
     EXPECT_EQ(1u, writer_->frame_count());
     EXPECT_TRUE(writer_->stop_waiting_frames().empty());
   } else {
     EXPECT_EQ(2u, writer_->frame_count());
     EXPECT_FALSE(writer_->stop_waiting_frames().empty());
   }
   EXPECT_FALSE(writer_->ack_frames().empty());
   EXPECT_FALSE(connection_.GetAckAlarm()->IsSet());
 }

 TEST_P(QuicConnectionTest, SendDelayedAckDecimationWithReorderingEighthRtt) {
   EXPECT_CALL(visitor_, OnAckNeedsRetransmittableFrame()).Times(AnyNumber());
   QuicConnectionPeer::SetAckMode(&connection_, ACK_DECIMATION_WITH_REORDERING);
   QuicConnectionPeer::SetAckDecimationDelay(&connection_, 0.125);

   const size_t kMinRttMs = 40;
   RttStats* rtt_stats = const_cast<RttStats*>(manager_->GetRttStats());
   rtt_stats->UpdateRtt(QuicTime::Delta::FromMilliseconds(kMinRttMs),
                        QuicTime::Delta::Zero(), QuicTime::Zero());
   // The ack time should be based on min_rtt/8, since it's less than the
   // default delayed ack time.
   QuicTime ack_time = clock_.ApproximateNow() +
                       QuicTime::Delta::FromMilliseconds(kMinRttMs / 8);
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
   EXPECT_FALSE(connection_.GetAckAlarm()->IsSet());
   const uint8_t tag = 0x07;
   SetDecrypter(ENCRYPTION_ZERO_RTT,
                std::make_unique<StrictTaggingDecrypter>(tag));
   peer_framer_.SetEncrypter(ENCRYPTION_ZERO_RTT,
                             std::make_unique<TaggingEncrypter>(tag));
   // Process a packet from the non-crypto stream.
   frame1_.stream_id = 3;

   // Process all the initial packets in order so there aren't missing packets.
   uint64_t kFirstDecimatedPacket = 101;
   for (unsigned int i = 0; i < kFirstDecimatedPacket - 1; ++i) {
     EXPECT_CALL(visitor_, OnStreamFrame(_)).Times(1);
     ProcessDataPacketAtLevel(1 + i, !kHasStopWaiting, ENCRYPTION_ZERO_RTT);
   }
   EXPECT_FALSE(connection_.GetAckAlarm()->IsSet());
   // The same as ProcessPacket(1) except that ENCRYPTION_ZERO_RTT is used
   // instead of ENCRYPTION_INITIAL.
   EXPECT_CALL(visitor_, OnStreamFrame(_)).Times(1);
   ProcessDataPacketAtLevel(kFirstDecimatedPacket, !kHasStopWaiting,
                            ENCRYPTION_ZERO_RTT);

   // Check if delayed ack timer is running for the expected interval.
   EXPECT_TRUE(connection_.GetAckAlarm()->IsSet());
   EXPECT_EQ(ack_time, connection_.GetAckAlarm()->deadline());

   // Process packet 10 first and ensure the alarm is one eighth min_rtt.
   EXPECT_CALL(visitor_, OnStreamFrame(_)).Times(1);
   ProcessDataPacketAtLevel(kFirstDecimatedPacket + 9, !kHasStopWaiting,
                            ENCRYPTION_ZERO_RTT);
   ack_time = clock_.ApproximateNow() + QuicTime::Delta::FromMilliseconds(5);
   EXPECT_TRUE(connection_.GetAckAlarm()->IsSet());
   EXPECT_EQ(ack_time, connection_.GetAckAlarm()->deadline());

   // The 10th received packet causes an ack to be sent.
   for (int i = 0; i < 8; ++i) {
     EXPECT_TRUE(connection_.GetAckAlarm()->IsSet());
     EXPECT_CALL(visitor_, OnStreamFrame(_)).Times(1);
     ProcessDataPacketAtLevel(kFirstDecimatedPacket + 1 + i, !kHasStopWaiting,
                              ENCRYPTION_ZERO_RTT);
   }
   // Check that ack is sent and that delayed ack alarm is reset.
   size_t padding_frame_count = writer_->padding_frames().size();
   if (GetParam().no_stop_waiting) {
     EXPECT_EQ(padding_frame_count + 1u, writer_->frame_count());
     EXPECT_TRUE(writer_->stop_waiting_frames().empty());
   } else {
     EXPECT_EQ(padding_frame_count + 2u, writer_->frame_count());
     EXPECT_FALSE(writer_->stop_waiting_frames().empty());
   }
   EXPECT_FALSE(writer_->ack_frames().empty());
   EXPECT_FALSE(connection_.GetAckAlarm()->IsSet());
 }

 TEST_P(QuicConnectionTest,
        SendDelayedAckDecimationWithLargeReorderingEighthRtt) {
   EXPECT_CALL(visitor_, OnAckNeedsRetransmittableFrame()).Times(AnyNumber());
   QuicConnectionPeer::SetAckMode(&connection_, ACK_DECIMATION_WITH_REORDERING);
   QuicConnectionPeer::SetAckDecimationDelay(&connection_, 0.125);

   const size_t kMinRttMs = 40;
   RttStats* rtt_stats = const_cast<RttStats*>(manager_->GetRttStats());
   rtt_stats->UpdateRtt(QuicTime::Delta::FromMilliseconds(kMinRttMs),
                        QuicTime::Delta::Zero(), QuicTime::Zero());
   // The ack time should be based on min_rtt/8, since it's less than the
   // default delayed ack time.
   QuicTime ack_time = clock_.ApproximateNow() +
                       QuicTime::Delta::FromMilliseconds(kMinRttMs / 8);
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
   EXPECT_FALSE(connection_.GetAckAlarm()->IsSet());
   const uint8_t tag = 0x07;
   SetDecrypter(ENCRYPTION_ZERO_RTT,
                std::make_unique<StrictTaggingDecrypter>(tag));
   peer_framer_.SetEncrypter(ENCRYPTION_ZERO_RTT,
                             std::make_unique<TaggingEncrypter>(tag));
   // Process a packet from the non-crypto stream.
   frame1_.stream_id = 3;

   // Process all the initial packets in order so there aren't missing packets.
   uint64_t kFirstDecimatedPacket = 101;
   for (unsigned int i = 0; i < kFirstDecimatedPacket - 1; ++i) {
     EXPECT_CALL(visitor_, OnStreamFrame(_)).Times(1);
     ProcessDataPacketAtLevel(1 + i, !kHasStopWaiting, ENCRYPTION_ZERO_RTT);
   }
   EXPECT_FALSE(connection_.GetAckAlarm()->IsSet());
   // The same as ProcessPacket(1) except that ENCRYPTION_ZERO_RTT is used
   // instead of ENCRYPTION_INITIAL.
   EXPECT_CALL(visitor_, OnStreamFrame(_)).Times(1);
   ProcessDataPacketAtLevel(kFirstDecimatedPacket, !kHasStopWaiting,
                            ENCRYPTION_ZERO_RTT);

   // Check if delayed ack timer is running for the expected interval.
   EXPECT_TRUE(connection_.GetAckAlarm()->IsSet());
   EXPECT_EQ(ack_time, connection_.GetAckAlarm()->deadline());

   // Process packet 10 first and ensure the alarm is one eighth min_rtt.
   EXPECT_CALL(visitor_, OnStreamFrame(_)).Times(1);
   ProcessDataPacketAtLevel(kFirstDecimatedPacket + 19, !kHasStopWaiting,
                            ENCRYPTION_ZERO_RTT);
   ack_time = clock_.ApproximateNow() + QuicTime::Delta::FromMilliseconds(5);
   EXPECT_TRUE(connection_.GetAckAlarm()->IsSet());
   EXPECT_EQ(ack_time, connection_.GetAckAlarm()->deadline());

   // The 10th received packet causes an ack to be sent.
   for (int i = 0; i < 8; ++i) {
     EXPECT_TRUE(connection_.GetAckAlarm()->IsSet());
     EXPECT_CALL(visitor_, OnStreamFrame(_)).Times(1);
     ProcessDataPacketAtLevel(kFirstDecimatedPacket + 1 + i, !kHasStopWaiting,
                              ENCRYPTION_ZERO_RTT);
   }
   // Check that ack is sent and that delayed ack alarm is reset.
   if (GetParam().no_stop_waiting) {
     EXPECT_EQ(1u, writer_->frame_count());
     EXPECT_TRUE(writer_->stop_waiting_frames().empty());
   } else {
     EXPECT_EQ(2u, writer_->frame_count());
     EXPECT_FALSE(writer_->stop_waiting_frames().empty());
   }
   EXPECT_FALSE(writer_->ack_frames().empty());
   EXPECT_FALSE(connection_.GetAckAlarm()->IsSet());

   // The next packet received in order will cause an immediate ack,
   // because it fills a hole.
   EXPECT_FALSE(connection_.GetAckAlarm()->IsSet());
   EXPECT_CALL(visitor_, OnStreamFrame(_)).Times(1);
   ProcessDataPacketAtLevel(kFirstDecimatedPacket + 10, !kHasStopWaiting,
                            ENCRYPTION_ZERO_RTT);
   // Check that ack is sent and that delayed ack alarm is reset.
   if (GetParam().no_stop_waiting) {
     EXPECT_EQ(1u, writer_->frame_count());
     EXPECT_TRUE(writer_->stop_waiting_frames().empty());
   } else {
     EXPECT_EQ(2u, writer_->frame_count());
     EXPECT_FALSE(writer_->stop_waiting_frames().empty());
   }
   EXPECT_FALSE(writer_->ack_frames().empty());
   EXPECT_FALSE(connection_.GetAckAlarm()->IsSet());
 }

 TEST_P(QuicConnectionTest, SendDelayedAckOnHandshakeConfirmed) {
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
   ProcessPacket(1);
   // Check that ack is sent and that delayed ack alarm is set.
   EXPECT_TRUE(connection_.GetAckAlarm()->IsSet());
   QuicTime ack_time = clock_.ApproximateNow() + DefaultDelayedAckTime();
   EXPECT_EQ(ack_time, connection_.GetAckAlarm()->deadline());

   // Completing the handshake as the server does nothing.
   QuicConnectionPeer::SetPerspective(&connection_, Perspective::IS_SERVER);
   connection_.OnHandshakeComplete();
   EXPECT_TRUE(connection_.GetAckAlarm()->IsSet());
   EXPECT_EQ(ack_time, connection_.GetAckAlarm()->deadline());

   // Complete the handshake as the client decreases the delayed ack time to 0ms.
   QuicConnectionPeer::SetPerspective(&connection_, Perspective::IS_CLIENT);
   connection_.OnHandshakeComplete();
   EXPECT_TRUE(connection_.GetAckAlarm()->IsSet());
   EXPECT_EQ(clock_.ApproximateNow(), connection_.GetAckAlarm()->deadline());
 }

 TEST_P(QuicConnectionTest, SendDelayedAckOnSecondPacket) {
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
   ProcessPacket(1);
   ProcessPacket(2);
   // Check that ack is sent and that delayed ack alarm is reset.
   size_t padding_frame_count = writer_->padding_frames().size();
   if (GetParam().no_stop_waiting) {
     EXPECT_EQ(padding_frame_count + 1u, writer_->frame_count());
     EXPECT_TRUE(writer_->stop_waiting_frames().empty());
   } else {
     EXPECT_EQ(padding_frame_count + 2u, writer_->frame_count());
     EXPECT_FALSE(writer_->stop_waiting_frames().empty());
   }
   EXPECT_FALSE(writer_->ack_frames().empty());
   EXPECT_FALSE(connection_.GetAckAlarm()->IsSet());
 }

 TEST_P(QuicConnectionTest, NoAckOnOldNacks) {
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(0);
   ProcessPacket(2);
   size_t frames_per_ack = GetParam().no_stop_waiting ? 1 : 2;

   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(1);
   ProcessPacket(3);
   size_t padding_frame_count = writer_->padding_frames().size();
   EXPECT_EQ(padding_frame_count + frames_per_ack, writer_->frame_count());
   EXPECT_FALSE(writer_->ack_frames().empty());
   writer_->Reset();

   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(0);
   ProcessPacket(4);
   EXPECT_EQ(0u, writer_->frame_count());

   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(1);
   ProcessPacket(5);
   padding_frame_count = writer_->padding_frames().size();
   EXPECT_EQ(padding_frame_count + frames_per_ack, writer_->frame_count());
   EXPECT_FALSE(writer_->ack_frames().empty());
   writer_->Reset();

   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(0);
   // Now only set the timer on the 6th packet, instead of sending another ack.
   ProcessPacket(6);
   padding_frame_count = writer_->padding_frames().size();
   EXPECT_EQ(padding_frame_count, writer_->frame_count());
   EXPECT_TRUE(connection_.GetAckAlarm()->IsSet());
 }

 TEST_P(QuicConnectionTest, SendDelayedAckOnOutgoingPacket) {
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
   EXPECT_CALL(visitor_, OnStreamFrame(_));
   peer_framer_.SetEncrypter(ENCRYPTION_FORWARD_SECURE,
                             std::make_unique<TaggingEncrypter>(0x01));
   SetDecrypter(ENCRYPTION_FORWARD_SECURE,
                std::make_unique<StrictTaggingDecrypter>(0x01));
   ProcessDataPacket(1);
   connection_.SendStreamDataWithString(
       GetNthClientInitiatedStreamId(1, connection_.transport_version()), "foo",
       0, NO_FIN);
   // Check that ack is bundled with outgoing data and that delayed ack
   // alarm is reset.
   if (GetParam().no_stop_waiting) {
     EXPECT_EQ(2u, writer_->frame_count());
     EXPECT_TRUE(writer_->stop_waiting_frames().empty());
   } else {
     EXPECT_EQ(3u, writer_->frame_count());
     EXPECT_FALSE(writer_->stop_waiting_frames().empty());
   }
   EXPECT_FALSE(writer_->ack_frames().empty());
   EXPECT_FALSE(connection_.GetAckAlarm()->IsSet());
 }

 TEST_P(QuicConnectionTest, SendDelayedAckOnOutgoingCryptoPacket) {
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
   if (QuicVersionUsesCryptoFrames(connection_.transport_version())) {
     EXPECT_CALL(visitor_, OnCryptoFrame(_)).Times(1);
   } else {
     EXPECT_CALL(visitor_, OnStreamFrame(_)).Times(1);
   }
   ProcessCryptoPacketAtLevel(1, ENCRYPTION_INITIAL);
   connection_.SendCryptoDataWithString("foo", 0);
   // Check that ack is bundled with outgoing crypto data.
   if (GetParam().no_stop_waiting) {
     EXPECT_EQ(3u, writer_->frame_count());
     EXPECT_TRUE(writer_->stop_waiting_frames().empty());
   } else {
     EXPECT_EQ(4u, writer_->frame_count());
     EXPECT_FALSE(writer_->stop_waiting_frames().empty());
   }
   EXPECT_FALSE(connection_.GetAckAlarm()->IsSet());
 }

 TEST_P(QuicConnectionTest, BlockAndBufferOnFirstCHLOPacketOfTwo) {
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
   ProcessPacket(1);
   BlockOnNextWrite();
   writer_->set_is_write_blocked_data_buffered(true);
   connection_.SendCryptoDataWithString("foo", 0);
   EXPECT_TRUE(writer_->IsWriteBlocked());
   EXPECT_FALSE(connection_.HasQueuedData());
   connection_.SendCryptoDataWithString("bar", 3);
   EXPECT_TRUE(writer_->IsWriteBlocked());
   EXPECT_TRUE(connection_.HasQueuedData());
 }

 TEST_P(QuicConnectionTest, BundleAckForSecondCHLO) {
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
   EXPECT_FALSE(connection_.GetAckAlarm()->IsSet());
   EXPECT_CALL(visitor_, OnCanWrite())
       .WillOnce(IgnoreResult(InvokeWithoutArgs(
           &connection_, &TestConnection::SendCryptoStreamData)));
   // Process a packet from the crypto stream, which is frame1_'s default.
   // Receiving the CHLO as packet 2 first will cause the connection to
   // immediately send an ack, due to the packet gap.
   if (QuicVersionUsesCryptoFrames(connection_.transport_version())) {
     EXPECT_CALL(visitor_, OnCryptoFrame(_)).Times(1);
   } else {
     EXPECT_CALL(visitor_, OnStreamFrame(_)).Times(1);
   }
   ProcessCryptoPacketAtLevel(2, ENCRYPTION_INITIAL);
   // Check that ack is sent and that delayed ack alarm is reset.
   if (GetParam().no_stop_waiting) {
     EXPECT_EQ(3u, writer_->frame_count());
     EXPECT_TRUE(writer_->stop_waiting_frames().empty());
   } else {
     EXPECT_EQ(4u, writer_->frame_count());
     EXPECT_FALSE(writer_->stop_waiting_frames().empty());
   }
   if (!QuicVersionUsesCryptoFrames(connection_.transport_version())) {
     EXPECT_EQ(1u, writer_->stream_frames().size());
   } else {
     EXPECT_EQ(1u, writer_->crypto_frames().size());
   }
   EXPECT_EQ(1u, writer_->padding_frames().size());
   ASSERT_FALSE(writer_->ack_frames().empty());
   EXPECT_EQ(QuicPacketNumber(2u), LargestAcked(writer_->ack_frames().front()));
   EXPECT_FALSE(connection_.GetAckAlarm()->IsSet());
 }

 TEST_P(QuicConnectionTest, BundleAckForSecondCHLOTwoPacketReject) {
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
   EXPECT_FALSE(connection_.GetAckAlarm()->IsSet());

   // Process two packets from the crypto stream, which is frame1_'s default,
   // simulating a 2 packet reject.
   {
     if (QuicVersionUsesCryptoFrames(connection_.transport_version())) {
       EXPECT_CALL(visitor_, OnCryptoFrame(_)).Times(1);
     } else {
       EXPECT_CALL(visitor_, OnStreamFrame(_)).Times(1);
     }
     ProcessCryptoPacketAtLevel(1, ENCRYPTION_INITIAL);
     // Send the new CHLO when the REJ is processed.
     if (QuicVersionUsesCryptoFrames(connection_.transport_version())) {
       EXPECT_CALL(visitor_, OnCryptoFrame(_))
           .WillOnce(IgnoreResult(InvokeWithoutArgs(
               &connection_, &TestConnection::SendCryptoStreamData)));
     } else {
       EXPECT_CALL(visitor_, OnStreamFrame(_))
           .WillOnce(IgnoreResult(InvokeWithoutArgs(
               &connection_, &TestConnection::SendCryptoStreamData)));
     }
     ProcessCryptoPacketAtLevel(2, ENCRYPTION_INITIAL);
   }
   // Check that ack is sent and that delayed ack alarm is reset.
   if (GetParam().no_stop_waiting) {
     EXPECT_EQ(3u, writer_->frame_count());
     EXPECT_TRUE(writer_->stop_waiting_frames().empty());
   } else {
     EXPECT_EQ(4u, writer_->frame_count());
     EXPECT_FALSE(writer_->stop_waiting_frames().empty());
   }
   if (!QuicVersionUsesCryptoFrames(connection_.transport_version())) {
     EXPECT_EQ(1u, writer_->stream_frames().size());
   } else {
     EXPECT_EQ(1u, writer_->crypto_frames().size());
   }
   EXPECT_EQ(1u, writer_->padding_frames().size());
   ASSERT_FALSE(writer_->ack_frames().empty());
   EXPECT_EQ(QuicPacketNumber(2u), LargestAcked(writer_->ack_frames().front()));
   EXPECT_FALSE(connection_.GetAckAlarm()->IsSet());
 }

 TEST_P(QuicConnectionTest, BundleAckWithDataOnIncomingAck) {
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
   connection_.SendStreamDataWithString(
       GetNthClientInitiatedStreamId(1, connection_.transport_version()), "foo",
       0, NO_FIN);
   connection_.SendStreamDataWithString(
       GetNthClientInitiatedStreamId(1, connection_.transport_version()), "foo",
       3, NO_FIN);
   // Ack the second packet, which will retransmit the first packet.
   QuicAckFrame ack = ConstructAckFrame(2, 1);
   LostPacketVector lost_packets;
   lost_packets.push_back(
       LostPacket(QuicPacketNumber(1), kMaxOutgoingPacketSize));
   EXPECT_CALL(*loss_algorithm_, DetectLosses(_, _, _, _, _, _))
       .WillOnce(SetArgPointee<5>(lost_packets));
   EXPECT_CALL(*send_algorithm_, OnCongestionEvent(true, _, _, _, _));
   ProcessAckPacket(&ack);
   size_t padding_frame_count = writer_->padding_frames().size();
   EXPECT_EQ(padding_frame_count + 1u, writer_->frame_count());
   EXPECT_EQ(1u, writer_->stream_frames().size());
   writer_->Reset();

   // Now ack the retransmission, which will both raise the high water mark
   // and see if there is more data to send.
   ack = ConstructAckFrame(3, 1);
   EXPECT_CALL(*loss_algorithm_, DetectLosses(_, _, _, _, _, _));
   EXPECT_CALL(*send_algorithm_, OnCongestionEvent(true, _, _, _, _));
   ProcessAckPacket(&ack);

   // Check that no packet is sent and the ack alarm isn't set.
   EXPECT_EQ(0u, writer_->frame_count());
   EXPECT_FALSE(connection_.GetAckAlarm()->IsSet());
   writer_->Reset();

   // Send the same ack, but send both data and an ack together.
   ack = ConstructAckFrame(3, 1);
   EXPECT_CALL(*loss_algorithm_, DetectLosses(_, _, _, _, _, _));
   EXPECT_CALL(visitor_, OnCanWrite())
       .WillOnce(IgnoreResult(InvokeWithoutArgs(
           &connection_, &TestConnection::EnsureWritableAndSendStreamData5)));
   ProcessAckPacket(&ack);

   // Check that ack is bundled with outgoing data and the delayed ack
   // alarm is reset.
   if (GetParam().no_stop_waiting) {
     if (GetQuicReloadableFlag(quic_simplify_stop_waiting)) {
       // Do not ACK acks.
       EXPECT_EQ(1u, writer_->frame_count());
     } else {
       EXPECT_EQ(2u, writer_->frame_count());
       EXPECT_TRUE(writer_->stop_waiting_frames().empty());
     }
   } else {
     EXPECT_EQ(3u, writer_->frame_count());
     EXPECT_FALSE(writer_->stop_waiting_frames().empty());
   }
   if (GetParam().no_stop_waiting &&
       GetQuicReloadableFlag(quic_simplify_stop_waiting)) {
     EXPECT_TRUE(writer_->ack_frames().empty());
   } else {
     EXPECT_FALSE(writer_->ack_frames().empty());
     EXPECT_EQ(QuicPacketNumber(3u),
               LargestAcked(writer_->ack_frames().front()));
   }
   EXPECT_EQ(1u, writer_->stream_frames().size());
   EXPECT_FALSE(connection_.GetAckAlarm()->IsSet());
 }

 TEST_P(QuicConnectionTest, NoAckSentForClose) {
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
   ProcessPacket(1);
   EXPECT_CALL(visitor_, OnConnectionClosed(_, ConnectionCloseSource::FROM_PEER))
       .WillOnce(Invoke(this, &QuicConnectionTest::SaveConnectionCloseFrame));
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(0);
   ProcessClosePacket(2);
   EXPECT_EQ(1, connection_close_frame_count_);
   EXPECT_EQ(QUIC_PEER_GOING_AWAY,
             saved_connection_close_frame_.quic_error_code);
 }

 TEST_P(QuicConnectionTest, SendWhenDisconnected) {
   EXPECT_TRUE(connection_.connected());
   EXPECT_CALL(visitor_, OnConnectionClosed(_, ConnectionCloseSource::FROM_SELF))
       .WillOnce(Invoke(this, &QuicConnectionTest::SaveConnectionCloseFrame));
   connection_.CloseConnection(QUIC_PEER_GOING_AWAY, "no reason",
                               ConnectionCloseBehavior::SILENT_CLOSE);
   EXPECT_FALSE(connection_.connected());
   EXPECT_FALSE(connection_.CanWriteStreamData());
   std::unique_ptr<QuicPacket> packet =
       ConstructDataPacket(1, !kHasStopWaiting, ENCRYPTION_INITIAL);
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, QuicPacketNumber(1), _, _))
       .Times(0);
   connection_.SendPacket(ENCRYPTION_INITIAL, 1, std::move(packet),
                          HAS_RETRANSMITTABLE_DATA, false, false);
   EXPECT_EQ(1, connection_close_frame_count_);
   EXPECT_EQ(QUIC_PEER_GOING_AWAY,
             saved_connection_close_frame_.quic_error_code);
 }

 TEST_P(QuicConnectionTest, SendConnectivityProbingWhenDisconnected) {
   // EXPECT_QUIC_BUG tests are expensive so only run one instance of them.
   if (!IsDefaultTestConfiguration()) {
     return;
   }

   EXPECT_TRUE(connection_.connected());
   EXPECT_CALL(visitor_, OnConnectionClosed(_, ConnectionCloseSource::FROM_SELF))
       .WillOnce(Invoke(this, &QuicConnectionTest::SaveConnectionCloseFrame));
   connection_.CloseConnection(QUIC_PEER_GOING_AWAY, "no reason",
                               ConnectionCloseBehavior::SILENT_CLOSE);
   EXPECT_FALSE(connection_.connected());
   EXPECT_FALSE(connection_.CanWriteStreamData());

   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, QuicPacketNumber(1), _, _))
       .Times(0);

   EXPECT_QUIC_BUG(connection_.SendConnectivityProbingPacket(
                       writer_.get(), connection_.peer_address()),
                   "Not sending connectivity probing packet as connection is "
                   "disconnected.");
   EXPECT_EQ(1, connection_close_frame_count_);
   EXPECT_EQ(QUIC_PEER_GOING_AWAY,
             saved_connection_close_frame_.quic_error_code);
 }

 TEST_P(QuicConnectionTest, WriteBlockedAfterClientSendsConnectivityProbe) {
   EXPECT_EQ(Perspective::IS_CLIENT, connection_.perspective());
   TestPacketWriter probing_writer(version(), &clock_);
   // Block next write so that sending connectivity probe will encounter a
   // blocked write when send a connectivity probe to the peer.
   probing_writer.BlockOnNextWrite();
   // Connection will not be marked as write blocked as connectivity probe only
   // affects the probing_writer which is not the default.
   EXPECT_CALL(visitor_, OnWriteBlocked()).Times(0);

   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, QuicPacketNumber(1), _, _))
       .Times(1);
   connection_.SendConnectivityProbingPacket(&probing_writer,
                                             connection_.peer_address());
 }

 TEST_P(QuicConnectionTest, WriterBlockedAfterServerSendsConnectivityProbe) {
   set_perspective(Perspective::IS_SERVER);
   QuicPacketCreatorPeer::SetSendVersionInPacket(creator_, false);

   // Block next write so that sending connectivity probe will encounter a
   // blocked write when send a connectivity probe to the peer.
   writer_->BlockOnNextWrite();
   // Connection will be marked as write blocked as server uses the default
   // writer to send connectivity probes.
   EXPECT_CALL(visitor_, OnWriteBlocked()).Times(1);

   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, QuicPacketNumber(1), _, _))
       .Times(1);
   connection_.SendConnectivityProbingPacket(writer_.get(),
                                             connection_.peer_address());
 }

 TEST_P(QuicConnectionTest, WriterErrorWhenClientSendsConnectivityProbe) {
   EXPECT_EQ(Perspective::IS_CLIENT, connection_.perspective());
   TestPacketWriter probing_writer(version(), &clock_);
   probing_writer.SetShouldWriteFail();

   // Connection should not be closed if a connectivity probe is failed to be
   // sent.
   EXPECT_CALL(visitor_, OnConnectionClosed(_, _)).Times(0);

   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, QuicPacketNumber(1), _, _))
       .Times(0);
   connection_.SendConnectivityProbingPacket(&probing_writer,
                                             connection_.peer_address());
 }

 TEST_P(QuicConnectionTest, WriterErrorWhenServerSendsConnectivityProbe) {
   set_perspective(Perspective::IS_SERVER);
   QuicPacketCreatorPeer::SetSendVersionInPacket(creator_, false);

   writer_->SetShouldWriteFail();
   // Connection should not be closed if a connectivity probe is failed to be
   // sent.
   EXPECT_CALL(visitor_, OnConnectionClosed(_, _)).Times(0);

   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, QuicPacketNumber(1), _, _))
       .Times(0);
   connection_.SendConnectivityProbingPacket(writer_.get(),
                                             connection_.peer_address());
 }

 TEST_P(QuicConnectionTest, PublicReset) {
   if (VersionHasIetfInvariantHeader(GetParam().version.transport_version)) {
     return;
   }
   QuicPublicResetPacket header;
   // Public reset packet in only built by server.
   header.connection_id = connection_id_;
   std::unique_ptr<QuicEncryptedPacket> packet(
       framer_.BuildPublicResetPacket(header));
   std::unique_ptr<QuicReceivedPacket> received(
       ConstructReceivedPacket(*packet, QuicTime::Zero()));
   EXPECT_CALL(visitor_, OnConnectionClosed(_, ConnectionCloseSource::FROM_PEER))
       .WillOnce(Invoke(this, &QuicConnectionTest::SaveConnectionCloseFrame));
   connection_.ProcessUdpPacket(kSelfAddress, kPeerAddress, *received);
   EXPECT_EQ(1, connection_close_frame_count_);
   EXPECT_EQ(QUIC_PUBLIC_RESET, saved_connection_close_frame_.quic_error_code);
 }

 TEST_P(QuicConnectionTest, IetfStatelessReset) {
   if (!VersionHasIetfInvariantHeader(GetParam().version.transport_version)) {
     return;
   }
   const QuicUint128 kTestStatelessResetToken = 1010101;
   QuicConfig config;
   QuicConfigPeer::SetReceivedStatelessResetToken(&config,
                                                  kTestStatelessResetToken);
   EXPECT_CALL(*send_algorithm_, SetFromConfig(_, _));
   connection_.SetFromConfig(config);
   std::unique_ptr<QuicEncryptedPacket> packet(
       QuicFramer::BuildIetfStatelessResetPacket(connection_id_,
                                                 kTestStatelessResetToken));
   std::unique_ptr<QuicReceivedPacket> received(
       ConstructReceivedPacket(*packet, QuicTime::Zero()));
   EXPECT_CALL(visitor_, OnConnectionClosed(_, ConnectionCloseSource::FROM_PEER))
       .WillOnce(Invoke(this, &QuicConnectionTest::SaveConnectionCloseFrame));
   connection_.ProcessUdpPacket(kSelfAddress, kPeerAddress, *received);
   EXPECT_EQ(1, connection_close_frame_count_);
   EXPECT_EQ(QUIC_PUBLIC_RESET, saved_connection_close_frame_.quic_error_code);
 }

 TEST_P(QuicConnectionTest, GoAway) {
   if (VersionHasIetfQuicFrames(GetParam().version.transport_version)) {
     // GoAway is not available in version 99.
     return;
   }

   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));

   QuicGoAwayFrame goaway;
   goaway.last_good_stream_id = 1;
   goaway.error_code = QUIC_PEER_GOING_AWAY;
   goaway.reason_phrase = "Going away.";
   EXPECT_CALL(visitor_, OnGoAway(_));
   ProcessGoAwayPacket(&goaway);
 }

 TEST_P(QuicConnectionTest, WindowUpdate) {
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));

   QuicWindowUpdateFrame window_update;
   window_update.stream_id = 3;
   window_update.byte_offset = 1234;
   EXPECT_CALL(visitor_, OnWindowUpdateFrame(_));
   ProcessFramePacket(QuicFrame(&window_update));
 }

 TEST_P(QuicConnectionTest, Blocked) {
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));

   QuicBlockedFrame blocked;
   blocked.stream_id = 3;
   EXPECT_CALL(visitor_, OnBlockedFrame(_));
   ProcessFramePacket(QuicFrame(&blocked));
   EXPECT_EQ(1u, connection_.GetStats().blocked_frames_received);
   EXPECT_EQ(0u, connection_.GetStats().blocked_frames_sent);
 }

 TEST_P(QuicConnectionTest, ZeroBytePacket) {
   // Don't close the connection for zero byte packets.
   EXPECT_CALL(visitor_, OnConnectionClosed(_, _)).Times(0);
   QuicReceivedPacket encrypted(nullptr, 0, QuicTime::Zero());
   connection_.ProcessUdpPacket(kSelfAddress, kPeerAddress, encrypted);
 }

 TEST_P(QuicConnectionTest, MissingPacketsBeforeLeastUnacked) {
   if (VersionHasIetfInvariantHeader(GetParam().version.transport_version)) {
     return;
   }
   // Set the packet number of the ack packet to be least unacked (4).
   QuicPacketCreatorPeer::SetPacketNumber(&peer_creator_, 3);
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
   ProcessStopWaitingPacket(InitStopWaitingFrame(4));
   EXPECT_FALSE(connection_.ack_frame().packets.Empty());
 }

 TEST_P(QuicConnectionTest, ClientHandlesVersionNegotiation) {
   // All supported versions except the one the connection supports.
   ParsedQuicVersionVector versions;
   for (auto version : AllSupportedVersions()) {
     if (version != connection_.version()) {
       versions.push_back(version);
     }
   }

   // Send a version negotiation packet.
   std::unique_ptr<QuicEncryptedPacket> encrypted(
       QuicFramer::BuildVersionNegotiationPacket(
           connection_id_, EmptyQuicConnectionId(),
           VersionHasIetfInvariantHeader(connection_.transport_version()),
           connection_.version().HasLengthPrefixedConnectionIds(), versions));
   std::unique_ptr<QuicReceivedPacket> received(
       ConstructReceivedPacket(*encrypted, QuicTime::Zero()));
   EXPECT_CALL(visitor_, OnConnectionClosed(_, ConnectionCloseSource::FROM_SELF))
       .WillOnce(Invoke(this, &QuicConnectionTest::SaveConnectionCloseFrame));
   // Verify no connection close packet gets sent.
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(0);
   connection_.ProcessUdpPacket(kSelfAddress, kPeerAddress, *received);
   EXPECT_FALSE(connection_.connected());
   EXPECT_EQ(1, connection_close_frame_count_);
   EXPECT_EQ(QUIC_INVALID_VERSION,
             saved_connection_close_frame_.quic_error_code);
 }

 TEST_P(QuicConnectionTest, BadVersionNegotiation) {
   // Send a version negotiation packet with the version the client started with.
   // It should be rejected.
   EXPECT_CALL(visitor_, OnConnectionClosed(_, ConnectionCloseSource::FROM_SELF))
       .WillOnce(Invoke(this, &QuicConnectionTest::SaveConnectionCloseFrame));
   std::unique_ptr<QuicEncryptedPacket> encrypted(
       QuicFramer::BuildVersionNegotiationPacket(
           connection_id_, EmptyQuicConnectionId(),
           VersionHasIetfInvariantHeader(connection_.transport_version()),
           connection_.version().HasLengthPrefixedConnectionIds(),
           AllSupportedVersions()));
   std::unique_ptr<QuicReceivedPacket> received(
       ConstructReceivedPacket(*encrypted, QuicTime::Zero()));
   connection_.ProcessUdpPacket(kSelfAddress, kPeerAddress, *received);
   EXPECT_EQ(1, connection_close_frame_count_);
   EXPECT_EQ(QUIC_INVALID_VERSION_NEGOTIATION_PACKET,
             saved_connection_close_frame_.quic_error_code);
 }

 TEST_P(QuicConnectionTest, CheckSendStats) {
   if (connection_.PtoEnabled()) {
     return;
   }
   connection_.SetMaxTailLossProbes(0);

   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _));
   connection_.SendStreamDataWithString(3, "first", 0, NO_FIN);
   size_t first_packet_size = writer_->last_packet_size();

   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _));
   connection_.SendStreamDataWithString(5, "second", 0, NO_FIN);
   size_t second_packet_size = writer_->last_packet_size();

   // 2 retransmissions due to rto, 1 due to explicit nack.
   EXPECT_CALL(*send_algorithm_, OnRetransmissionTimeout(true));
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(3);

   // Retransmit due to RTO.
   clock_.AdvanceTime(QuicTime::Delta::FromSeconds(10));
   connection_.GetRetransmissionAlarm()->Fire();

   // Retransmit due to explicit nacks.
   QuicAckFrame nack_three =
       InitAckFrame({{QuicPacketNumber(2), QuicPacketNumber(3)},
                     {QuicPacketNumber(4), QuicPacketNumber(5)}});

   LostPacketVector lost_packets;
   lost_packets.push_back(
       LostPacket(QuicPacketNumber(1), kMaxOutgoingPacketSize));
   lost_packets.push_back(
       LostPacket(QuicPacketNumber(3), kMaxOutgoingPacketSize));
   EXPECT_CALL(*loss_algorithm_, DetectLosses(_, _, _, _, _, _))
       .WillOnce(SetArgPointee<5>(lost_packets));
   EXPECT_CALL(*send_algorithm_, OnCongestionEvent(true, _, _, _, _));
   if (!connection_.session_decides_what_to_write()) {
     EXPECT_CALL(visitor_, OnCanWrite());
   }
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
   ProcessAckPacket(&nack_three);

   EXPECT_CALL(*send_algorithm_, BandwidthEstimate())
       .WillOnce(Return(QuicBandwidth::Zero()));

   const QuicConnectionStats& stats = connection_.GetStats();
   // For IETF QUIC, version is not included as the encryption level switches to
   // FORWARD_SECURE in SendStreamDataWithString.
   size_t save_on_version =
       VersionHasIetfInvariantHeader(GetParam().version.transport_version)
           ? 0
           : kQuicVersionSize;
   EXPECT_EQ(3 * first_packet_size + 2 * second_packet_size - save_on_version,
             stats.bytes_sent);
   EXPECT_EQ(5u, stats.packets_sent);
   EXPECT_EQ(2 * first_packet_size + second_packet_size - save_on_version,
             stats.bytes_retransmitted);
   EXPECT_EQ(3u, stats.packets_retransmitted);
   EXPECT_EQ(1u, stats.rto_count);
   EXPECT_EQ(kDefaultMaxPacketSize, stats.max_packet_size);
 }

 TEST_P(QuicConnectionTest, ProcessFramesIfPacketClosedConnection) {
   // Construct a packet with stream frame and connection close frame.
   QuicPacketHeader header;
   if (peer_framer_.perspective() == Perspective::IS_SERVER) {
     header.source_connection_id = connection_id_;
     header.destination_connection_id_included = CONNECTION_ID_ABSENT;
     if (!VersionHasIetfInvariantHeader(peer_framer_.transport_version())) {
       header.source_connection_id_included = CONNECTION_ID_PRESENT;
     }
   } else {
     header.destination_connection_id = connection_id_;
     if (VersionHasIetfInvariantHeader(peer_framer_.transport_version())) {
       header.destination_connection_id_included = CONNECTION_ID_ABSENT;
     }
   }
   header.packet_number = QuicPacketNumber(1);
   header.version_flag = false;

   QuicErrorCode kQuicErrorCode = QUIC_PEER_GOING_AWAY;
   // This QuicConnectionCloseFrame will default to being for a Google QUIC
   // close. If doing IETF QUIC then set fields appropriately for CC/T or CC/A,
   // depending on the mapping.
   QuicConnectionCloseFrame qccf(peer_framer_.transport_version(),
                                 kQuicErrorCode, "",
                                 /*transport_close_frame_type=*/0);
   QuicFrames frames;
   frames.push_back(QuicFrame(frame1_));
   frames.push_back(QuicFrame(&qccf));
   std::unique_ptr<QuicPacket> packet(ConstructPacket(header, frames));
   EXPECT_TRUE(nullptr != packet);
   char buffer[kMaxOutgoingPacketSize];
   size_t encrypted_length = peer_framer_.EncryptPayload(
       ENCRYPTION_FORWARD_SECURE, QuicPacketNumber(1), *packet, buffer,
       kMaxOutgoingPacketSize);

   EXPECT_CALL(visitor_, OnConnectionClosed(_, ConnectionCloseSource::FROM_PEER))
       .WillOnce(Invoke(this, &QuicConnectionTest::SaveConnectionCloseFrame));
   EXPECT_CALL(visitor_, OnStreamFrame(_)).Times(1);
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));

   connection_.ProcessUdpPacket(
       kSelfAddress, kPeerAddress,
       QuicReceivedPacket(buffer, encrypted_length, QuicTime::Zero(), false));
   EXPECT_EQ(1, connection_close_frame_count_);
   EXPECT_EQ(QUIC_PEER_GOING_AWAY,
             saved_connection_close_frame_.extracted_error_code);
 }

 TEST_P(QuicConnectionTest, SelectMutualVersion) {
   connection_.SetSupportedVersions(AllSupportedVersions());
   // Set the connection to speak the lowest quic version.
   connection_.set_version(QuicVersionMin());
   EXPECT_EQ(QuicVersionMin(), connection_.version());

   // Pass in available versions which includes a higher mutually supported
   // version.  The higher mutually supported version should be selected.
   ParsedQuicVersionVector supported_versions = AllSupportedVersions();
   EXPECT_TRUE(connection_.SelectMutualVersion(supported_versions));
   EXPECT_EQ(QuicVersionMax(), connection_.version());

   // Expect that the lowest version is selected.
   // Ensure the lowest supported version is less than the max, unless they're
   // the same.
   ParsedQuicVersionVector lowest_version_vector;
   lowest_version_vector.push_back(QuicVersionMin());
   EXPECT_TRUE(connection_.SelectMutualVersion(lowest_version_vector));
   EXPECT_EQ(QuicVersionMin(), connection_.version());

   // Shouldn't be able to find a mutually supported version.
   ParsedQuicVersionVector unsupported_version;
   unsupported_version.push_back(UnsupportedQuicVersion());
   EXPECT_FALSE(connection_.SelectMutualVersion(unsupported_version));
 }

 TEST_P(QuicConnectionTest, ConnectionCloseWhenWritable) {
   EXPECT_FALSE(writer_->IsWriteBlocked());

   // Send a packet.
   connection_.SendStreamDataWithString(1, "foo", 0, NO_FIN);
   EXPECT_EQ(0u, connection_.NumQueuedPackets());
   EXPECT_EQ(1u, writer_->packets_write_attempts());

   TriggerConnectionClose();
   EXPECT_LE(2u, writer_->packets_write_attempts());
 }

 TEST_P(QuicConnectionTest, ConnectionCloseGettingWriteBlocked) {
   BlockOnNextWrite();
   TriggerConnectionClose();
   EXPECT_EQ(1u, writer_->packets_write_attempts());
   EXPECT_TRUE(writer_->IsWriteBlocked());
 }

 TEST_P(QuicConnectionTest, ConnectionCloseWhenWriteBlocked) {
   BlockOnNextWrite();
   connection_.SendStreamDataWithString(1, "foo", 0, NO_FIN);
   EXPECT_EQ(1u, connection_.NumQueuedPackets());
   EXPECT_EQ(1u, writer_->packets_write_attempts());
   EXPECT_TRUE(writer_->IsWriteBlocked());
   TriggerConnectionClose();
   EXPECT_EQ(1u, writer_->packets_write_attempts());
 }

 TEST_P(QuicConnectionTest, OnPacketSentDebugVisitor) {
   MockQuicConnectionDebugVisitor debug_visitor;
   connection_.set_debug_visitor(&debug_visitor);

   EXPECT_CALL(debug_visitor, OnPacketSent(_, _, _, _)).Times(1);
   connection_.SendStreamDataWithString(1, "foo", 0, NO_FIN);

   EXPECT_CALL(debug_visitor, OnPacketSent(_, _, _, _)).Times(1);
   connection_.SendConnectivityProbingPacket(writer_.get(),
                                             connection_.peer_address());
 }

 TEST_P(QuicConnectionTest, OnPacketHeaderDebugVisitor) {
   QuicPacketHeader header;
   header.packet_number = QuicPacketNumber(1);
   if (VersionHasIetfInvariantHeader(GetParam().version.transport_version)) {
     header.form = IETF_QUIC_LONG_HEADER_PACKET;
   }

   MockQuicConnectionDebugVisitor debug_visitor;
   connection_.set_debug_visitor(&debug_visitor);
   EXPECT_CALL(debug_visitor, OnPacketHeader(Ref(header))).Times(1);
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_)).Times(1);
   EXPECT_CALL(debug_visitor, OnSuccessfulVersionNegotiation(_)).Times(1);
   connection_.OnPacketHeader(header);
 }

 TEST_P(QuicConnectionTest, Pacing) {
   TestConnection server(connection_id_, kSelfAddress, helper_.get(),
                         alarm_factory_.get(), writer_.get(),
                         Perspective::IS_SERVER, version());
   TestConnection client(connection_id_, kPeerAddress, helper_.get(),
                         alarm_factory_.get(), writer_.get(),
                         Perspective::IS_CLIENT, version());
   EXPECT_FALSE(QuicSentPacketManagerPeer::UsingPacing(
       static_cast<const QuicSentPacketManager*>(
           &client.sent_packet_manager())));
   EXPECT_FALSE(QuicSentPacketManagerPeer::UsingPacing(
       static_cast<const QuicSentPacketManager*>(
           &server.sent_packet_manager())));
 }

 TEST_P(QuicConnectionTest, WindowUpdateInstigateAcks) {
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));

   // Send a WINDOW_UPDATE frame.
   QuicWindowUpdateFrame window_update;
   window_update.stream_id = 3;
   window_update.byte_offset = 1234;
   EXPECT_CALL(visitor_, OnWindowUpdateFrame(_));
   ProcessFramePacket(QuicFrame(&window_update));

   // Ensure that this has caused the ACK alarm to be set.
   QuicAlarm* ack_alarm = QuicConnectionPeer::GetAckAlarm(&connection_);
   EXPECT_TRUE(ack_alarm->IsSet());
 }

 TEST_P(QuicConnectionTest, BlockedFrameInstigateAcks) {
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));

   // Send a BLOCKED frame.
   QuicBlockedFrame blocked;
   blocked.stream_id = 3;
   EXPECT_CALL(visitor_, OnBlockedFrame(_));
   ProcessFramePacket(QuicFrame(&blocked));

   // Ensure that this has caused the ACK alarm to be set.
   QuicAlarm* ack_alarm = QuicConnectionPeer::GetAckAlarm(&connection_);
   EXPECT_TRUE(ack_alarm->IsSet());
 }

 TEST_P(QuicConnectionTest, ReevaluateTimeUntilSendOnAck) {
   // Enable pacing.
   EXPECT_CALL(*send_algorithm_, SetFromConfig(_, _));
   QuicConfig config;
   connection_.SetFromConfig(config);

   // Send two packets.  One packet is not sufficient because if it gets acked,
   // there will be no packets in flight after that and the pacer will always
   // allow the next packet in that situation.
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
   EXPECT_CALL(*send_algorithm_, CanSend(_)).WillRepeatedly(Return(true));
   connection_.SendStreamDataWithString(
       GetNthClientInitiatedStreamId(1, connection_.transport_version()), "foo",
       0, NO_FIN);
   connection_.SendStreamDataWithString(
       GetNthClientInitiatedStreamId(1, connection_.transport_version()), "bar",
       3, NO_FIN);
   connection_.OnCanWrite();

   // Schedule the next packet for a few milliseconds in future.
   QuicSentPacketManagerPeer::DisablePacerBursts(manager_);
   QuicTime scheduled_pacing_time =
       clock_.Now() + QuicTime::Delta::FromMilliseconds(5);
   QuicSentPacketManagerPeer::SetNextPacedPacketTime(manager_,
                                                     scheduled_pacing_time);

   // Send a packet and have it be blocked by congestion control.
   EXPECT_CALL(*send_algorithm_, CanSend(_)).WillRepeatedly(Return(false));
   connection_.SendStreamDataWithString(
       GetNthClientInitiatedStreamId(1, connection_.transport_version()), "baz",
       6, NO_FIN);
   EXPECT_FALSE(connection_.GetSendAlarm()->IsSet());

   // Process an ack and the send alarm will be set to the new 5ms delay.
   QuicAckFrame ack = InitAckFrame(1);
   EXPECT_CALL(*loss_algorithm_, DetectLosses(_, _, _, _, _, _));
   EXPECT_CALL(*send_algorithm_, OnCongestionEvent(true, _, _, _, _));
   EXPECT_CALL(*send_algorithm_, CanSend(_)).WillRepeatedly(Return(true));
   ProcessAckPacket(&ack);
   size_t padding_frame_count = writer_->padding_frames().size();
   EXPECT_EQ(padding_frame_count + 1u, writer_->frame_count());
   EXPECT_EQ(1u, writer_->stream_frames().size());
   EXPECT_TRUE(connection_.GetSendAlarm()->IsSet());
   EXPECT_EQ(scheduled_pacing_time, connection_.GetSendAlarm()->deadline());
   writer_->Reset();
 }

 TEST_P(QuicConnectionTest, SendAcksImmediately) {
   if (connection_.SupportsMultiplePacketNumberSpaces()) {
     return;
   }
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
   EXPECT_CALL(visitor_, OnStreamFrame(_)).Times(1);
   ProcessDataPacket(1);
   CongestionBlockWrites();
   SendAckPacketToPeer();
 }

 TEST_P(QuicConnectionTest, SendPingImmediately) {
   MockQuicConnectionDebugVisitor debug_visitor;
   connection_.set_debug_visitor(&debug_visitor);

   CongestionBlockWrites();
   connection_.SetDefaultEncryptionLevel(ENCRYPTION_FORWARD_SECURE);
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(1);
   EXPECT_CALL(debug_visitor, OnPacketSent(_, _, _, _)).Times(1);
   EXPECT_CALL(debug_visitor, OnPingSent()).Times(1);
   connection_.SendControlFrame(QuicFrame(QuicPingFrame(1)));
   EXPECT_FALSE(connection_.HasQueuedData());
 }

 TEST_P(QuicConnectionTest, SendBlockedImmediately) {
   MockQuicConnectionDebugVisitor debug_visitor;
   connection_.set_debug_visitor(&debug_visitor);

   connection_.SetDefaultEncryptionLevel(ENCRYPTION_FORWARD_SECURE);
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(1);
   EXPECT_CALL(debug_visitor, OnPacketSent(_, _, _, _)).Times(1);
   EXPECT_EQ(0u, connection_.GetStats().blocked_frames_sent);
   connection_.SendControlFrame(QuicFrame(new QuicBlockedFrame(1, 3)));
   EXPECT_EQ(1u, connection_.GetStats().blocked_frames_sent);
   EXPECT_FALSE(connection_.HasQueuedData());
 }

 TEST_P(QuicConnectionTest, FailedToSendBlockedFrames) {
   if (!connection_.SupportsMultiplePacketNumberSpaces()) {
     return;
   }
   MockQuicConnectionDebugVisitor debug_visitor;
   connection_.set_debug_visitor(&debug_visitor);
   QuicBlockedFrame blocked(1, 3);

   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(0);
   EXPECT_CALL(debug_visitor, OnPacketSent(_, _, _, _)).Times(0);
   EXPECT_EQ(0u, connection_.GetStats().blocked_frames_sent);
   connection_.SendControlFrame(QuicFrame(&blocked));
   EXPECT_EQ(0u, connection_.GetStats().blocked_frames_sent);
   EXPECT_FALSE(connection_.HasQueuedData());
 }

 TEST_P(QuicConnectionTest, SendingUnencryptedStreamDataFails) {
   // EXPECT_QUIC_BUG tests are expensive so only run one instance of them.
   if (!IsDefaultTestConfiguration()) {
     return;
   }

   EXPECT_CALL(visitor_, OnConnectionClosed(_, ConnectionCloseSource::FROM_SELF))
       .WillOnce(Invoke(this, &QuicConnectionTest::SaveConnectionCloseFrame));
   struct iovec iov;
   MakeIOVector("", &iov);
   EXPECT_QUIC_BUG(connection_.SaveAndSendStreamData(3, &iov, 1, 0, 0, FIN),
                   "Cannot send stream data with level: ENCRYPTION_INITIAL");
   EXPECT_FALSE(connection_.connected());
   EXPECT_EQ(1, connection_close_frame_count_);
   EXPECT_EQ(QUIC_ATTEMPT_TO_SEND_UNENCRYPTED_STREAM_DATA,
             saved_connection_close_frame_.quic_error_code);
 }

 TEST_P(QuicConnectionTest, SetRetransmissionAlarmForCryptoPacket) {
   EXPECT_TRUE(connection_.connected());
   EXPECT_FALSE(connection_.GetRetransmissionAlarm()->IsSet());

   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(1);
   connection_.SendCryptoStreamData();

   // Verify retransmission timer is correctly set after crypto packet has been
   // sent.
   EXPECT_TRUE(connection_.GetRetransmissionAlarm()->IsSet());
   QuicTime retransmission_time =
       QuicConnectionPeer::GetSentPacketManager(&connection_)
           ->GetRetransmissionTime();
   EXPECT_NE(retransmission_time, clock_.ApproximateNow());
   EXPECT_EQ(retransmission_time,
             connection_.GetRetransmissionAlarm()->deadline());

   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(1);
   connection_.GetRetransmissionAlarm()->Fire();
 }

 TEST_P(QuicConnectionTest, PathDegradingAlarmForCryptoPacket) {
   EXPECT_TRUE(connection_.connected());
   EXPECT_FALSE(connection_.GetPathDegradingAlarm()->IsSet());
   EXPECT_FALSE(connection_.IsPathDegrading());

   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(1);
   connection_.SendCryptoStreamData();

   EXPECT_TRUE(connection_.GetPathDegradingAlarm()->IsSet());
   EXPECT_FALSE(connection_.IsPathDegrading());
   QuicTime::Delta delay = QuicConnectionPeer::GetSentPacketManager(&connection_)
                               ->GetPathDegradingDelay();
   EXPECT_EQ(delay, connection_.GetPathDegradingAlarm()->deadline() -
                        clock_.ApproximateNow());

   // Fire the path degrading alarm, path degrading signal should be sent to
   // the visitor.
   EXPECT_CALL(visitor_, OnPathDegrading());
   clock_.AdvanceTime(delay);
   connection_.GetPathDegradingAlarm()->Fire();
   EXPECT_TRUE(connection_.IsPathDegrading());
   EXPECT_FALSE(connection_.GetPathDegradingAlarm()->IsSet());
 }

 // Includes regression test for b/69979024.
 TEST_P(QuicConnectionTest, PathDegradingAlarmForNonCryptoPackets) {
   EXPECT_TRUE(connection_.connected());
   EXPECT_FALSE(connection_.GetPathDegradingAlarm()->IsSet());
   EXPECT_FALSE(connection_.IsPathDegrading());

   const char data[] = "data";
   size_t data_size = strlen(data);
   QuicStreamOffset offset = 0;

   for (int i = 0; i < 2; ++i) {
     // Send a packet. Now there's a retransmittable packet on the wire, so the
     // path degrading alarm should be set.
     connection_.SendStreamDataWithString(
         GetNthClientInitiatedStreamId(1, connection_.transport_version()), data,
         offset, NO_FIN);
     offset += data_size;
     EXPECT_TRUE(connection_.GetPathDegradingAlarm()->IsSet());
     // Check the deadline of the path degrading alarm.
     QuicTime::Delta delay =
         QuicConnectionPeer::GetSentPacketManager(&connection_)
             ->GetPathDegradingDelay();
     EXPECT_EQ(delay, connection_.GetPathDegradingAlarm()->deadline() -
                          clock_.ApproximateNow());

     // Send a second packet. The path degrading alarm's deadline should remain
     // the same.
     // Regression test for b/69979024.
     clock_.AdvanceTime(QuicTime::Delta::FromMilliseconds(5));
     QuicTime prev_deadline = connection_.GetPathDegradingAlarm()->deadline();
     connection_.SendStreamDataWithString(
         GetNthClientInitiatedStreamId(1, connection_.transport_version()), data,
         offset, NO_FIN);
     offset += data_size;
     EXPECT_TRUE(connection_.GetPathDegradingAlarm()->IsSet());
     EXPECT_EQ(prev_deadline, connection_.GetPathDegradingAlarm()->deadline());

     // Now receive an ACK of the first packet. This should advance the path
     // degrading alarm's deadline since forward progress has been made.
     clock_.AdvanceTime(QuicTime::Delta::FromMilliseconds(5));
     if (i == 0) {
       EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
     }
     EXPECT_CALL(*send_algorithm_, OnCongestionEvent(true, _, _, _, _));
     QuicAckFrame frame = InitAckFrame(
         {{QuicPacketNumber(1u + 2u * i), QuicPacketNumber(2u + 2u * i)}});
     ProcessAckPacket(&frame);
     EXPECT_TRUE(connection_.GetPathDegradingAlarm()->IsSet());
     // Check the deadline of the path degrading alarm.
     delay = QuicConnectionPeer::GetSentPacketManager(&connection_)
                 ->GetPathDegradingDelay();
     EXPECT_EQ(delay, connection_.GetPathDegradingAlarm()->deadline() -
                          clock_.ApproximateNow());

     if (i == 0) {
       // Now receive an ACK of the second packet. Since there are no more
       // retransmittable packets on the wire, this should cancel the path
       // degrading alarm.
       clock_.AdvanceTime(QuicTime::Delta::FromMilliseconds(5));
       EXPECT_CALL(*send_algorithm_, OnCongestionEvent(true, _, _, _, _));
       frame = InitAckFrame({{QuicPacketNumber(2), QuicPacketNumber(3)}});
       ProcessAckPacket(&frame);
       EXPECT_FALSE(connection_.GetPathDegradingAlarm()->IsSet());
     } else {
       // Advance time to the path degrading alarm's deadline and simulate
       // firing the alarm.
       clock_.AdvanceTime(delay);
       EXPECT_CALL(visitor_, OnPathDegrading());
       connection_.GetPathDegradingAlarm()->Fire();
       EXPECT_FALSE(connection_.GetPathDegradingAlarm()->IsSet());
     }
   }
   EXPECT_TRUE(connection_.IsPathDegrading());
 }

 TEST_P(QuicConnectionTest, RetransmittableOnWireSetsPingAlarm) {
   const QuicTime::Delta retransmittable_on_wire_timeout =
       QuicTime::Delta::FromMilliseconds(50);
   connection_.set_retransmittable_on_wire_timeout(
       retransmittable_on_wire_timeout);

   EXPECT_TRUE(connection_.connected());
   EXPECT_CALL(visitor_, ShouldKeepConnectionAlive())
       .WillRepeatedly(Return(true));

   EXPECT_FALSE(connection_.GetPathDegradingAlarm()->IsSet());
   EXPECT_FALSE(connection_.IsPathDegrading());
   EXPECT_FALSE(connection_.GetPingAlarm()->IsSet());

   const char data[] = "data";
   size_t data_size = strlen(data);
   QuicStreamOffset offset = 0;

   // Send a packet.
   connection_.SendStreamDataWithString(1, data, offset, NO_FIN);
   offset += data_size;
   // Now there's a retransmittable packet on the wire, so the path degrading
   // alarm should be set.
   // The retransmittable-on-wire alarm should not be set.
   EXPECT_TRUE(connection_.GetPathDegradingAlarm()->IsSet());
   QuicTime::Delta delay = QuicConnectionPeer::GetSentPacketManager(&connection_)
                               ->GetPathDegradingDelay();
   EXPECT_EQ(delay, connection_.GetPathDegradingAlarm()->deadline() -
                        clock_.ApproximateNow());
   ASSERT_TRUE(connection_.sent_packet_manager().HasInFlightPackets());
   // The ping alarm is set for the ping timeout, not the shorter
   // retransmittable_on_wire_timeout.
   EXPECT_TRUE(connection_.GetPingAlarm()->IsSet());
   QuicTime::Delta ping_delay = QuicTime::Delta::FromSeconds(kPingTimeoutSecs);
   EXPECT_EQ(ping_delay,
             connection_.GetPingAlarm()->deadline() - clock_.ApproximateNow());

   // Now receive an ACK of the packet.
   clock_.AdvanceTime(QuicTime::Delta::FromMilliseconds(5));
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
   EXPECT_CALL(*send_algorithm_, OnCongestionEvent(true, _, _, _, _));
   QuicAckFrame frame =
       InitAckFrame({{QuicPacketNumber(1), QuicPacketNumber(2)}});
   ProcessAckPacket(&frame);
   // No more retransmittable packets on the wire, so the path degrading alarm
   // should be cancelled, and the ping alarm should be set to the
   // retransmittable_on_wire_timeout.
   EXPECT_FALSE(connection_.GetPathDegradingAlarm()->IsSet());
   EXPECT_TRUE(connection_.GetPingAlarm()->IsSet());
   EXPECT_EQ(retransmittable_on_wire_timeout,
             connection_.GetPingAlarm()->deadline() - clock_.ApproximateNow());

   // Simulate firing the ping alarm and sending a PING.
   clock_.AdvanceTime(retransmittable_on_wire_timeout);
   EXPECT_CALL(visitor_, SendPing()).WillOnce(Invoke([this]() {
     connection_.SendControlFrame(QuicFrame(QuicPingFrame(1)));
   }));
   connection_.GetPingAlarm()->Fire();

   // Now there's a retransmittable packet (PING) on the wire, so the path
   // degrading alarm should be set.
   EXPECT_TRUE(connection_.GetPathDegradingAlarm()->IsSet());
   delay = QuicConnectionPeer::GetSentPacketManager(&connection_)
               ->GetPathDegradingDelay();
   EXPECT_EQ(delay, connection_.GetPathDegradingAlarm()->deadline() -
                        clock_.ApproximateNow());
 }

 // This test verifies that the connection marks path as degrading and does not
 // spin timer to detect path degrading when a new packet is sent on the
 // degraded path.
 TEST_P(QuicConnectionTest, NoPathDegradingAlarmIfPathIsDegrading) {
   EXPECT_TRUE(connection_.connected());
   EXPECT_FALSE(connection_.GetPathDegradingAlarm()->IsSet());
   EXPECT_FALSE(connection_.IsPathDegrading());

   const char data[] = "data";
   size_t data_size = strlen(data);
   QuicStreamOffset offset = 0;

   // Send the first packet. Now there's a retransmittable packet on the wire, so
   // the path degrading alarm should be set.
   connection_.SendStreamDataWithString(1, data, offset, NO_FIN);
   offset += data_size;
   EXPECT_TRUE(connection_.GetPathDegradingAlarm()->IsSet());
   // Check the deadline of the path degrading alarm.
   QuicTime::Delta delay = QuicConnectionPeer::GetSentPacketManager(&connection_)
                               ->GetPathDegradingDelay();
   EXPECT_EQ(delay, connection_.GetPathDegradingAlarm()->deadline() -
                        clock_.ApproximateNow());

   // Send a second packet. The path degrading alarm's deadline should remain
   // the same.
   clock_.AdvanceTime(QuicTime::Delta::FromMilliseconds(5));
   QuicTime prev_deadline = connection_.GetPathDegradingAlarm()->deadline();
   connection_.SendStreamDataWithString(1, data, offset, NO_FIN);
   offset += data_size;
   EXPECT_TRUE(connection_.GetPathDegradingAlarm()->IsSet());
   EXPECT_EQ(prev_deadline, connection_.GetPathDegradingAlarm()->deadline());

   // Now receive an ACK of the first packet. This should advance the path
   // degrading alarm's deadline since forward progress has been made.
   clock_.AdvanceTime(QuicTime::Delta::FromMilliseconds(5));
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
   EXPECT_CALL(*send_algorithm_, OnCongestionEvent(true, _, _, _, _));
   QuicAckFrame frame =
       InitAckFrame({{QuicPacketNumber(1u), QuicPacketNumber(2u)}});
   ProcessAckPacket(&frame);
   EXPECT_TRUE(connection_.GetPathDegradingAlarm()->IsSet());
   // Check the deadline of the path degrading alarm.
   delay = QuicConnectionPeer::GetSentPacketManager(&connection_)
               ->GetPathDegradingDelay();
   EXPECT_EQ(delay, connection_.GetPathDegradingAlarm()->deadline() -
                        clock_.ApproximateNow());

   // Advance time to the path degrading alarm's deadline and simulate
   // firing the path degrading alarm. This path will be considered as
   // degrading.
   clock_.AdvanceTime(delay);
   EXPECT_CALL(visitor_, OnPathDegrading()).Times(1);
   connection_.GetPathDegradingAlarm()->Fire();
   EXPECT_FALSE(connection_.GetPathDegradingAlarm()->IsSet());
   EXPECT_TRUE(connection_.IsPathDegrading());

   clock_.AdvanceTime(QuicTime::Delta::FromMilliseconds(5));
   EXPECT_FALSE(connection_.GetPathDegradingAlarm()->IsSet());
   // Send a third packet. The path degrading alarm is no longer set but path
   // should still be marked as degrading.
   connection_.SendStreamDataWithString(1, data, offset, NO_FIN);
   offset += data_size;
   EXPECT_FALSE(connection_.GetPathDegradingAlarm()->IsSet());
   EXPECT_TRUE(connection_.IsPathDegrading());
 }

 // This test verifies that the connection unmarks path as degrarding and spins
 // the timer to detect future path degrading when forward progress is made
 // after path has been marked degrading.
 TEST_P(QuicConnectionTest, UnmarkPathDegradingOnForwardProgress) {
   EXPECT_TRUE(connection_.connected());
   EXPECT_FALSE(connection_.GetPathDegradingAlarm()->IsSet());
   EXPECT_FALSE(connection_.IsPathDegrading());

   const char data[] = "data";
   size_t data_size = strlen(data);
   QuicStreamOffset offset = 0;

   // Send the first packet. Now there's a retransmittable packet on the wire, so
   // the path degrading alarm should be set.
   connection_.SendStreamDataWithString(1, data, offset, NO_FIN);
   offset += data_size;
   EXPECT_TRUE(connection_.GetPathDegradingAlarm()->IsSet());
   // Check the deadline of the path degrading alarm.
   QuicTime::Delta delay = QuicConnectionPeer::GetSentPacketManager(&connection_)
                               ->GetPathDegradingDelay();
   EXPECT_EQ(delay, connection_.GetPathDegradingAlarm()->deadline() -
                        clock_.ApproximateNow());

   // Send a second packet. The path degrading alarm's deadline should remain
   // the same.
   clock_.AdvanceTime(QuicTime::Delta::FromMilliseconds(5));
   QuicTime prev_deadline = connection_.GetPathDegradingAlarm()->deadline();
   connection_.SendStreamDataWithString(1, data, offset, NO_FIN);
   offset += data_size;
   EXPECT_TRUE(connection_.GetPathDegradingAlarm()->IsSet());
   EXPECT_EQ(prev_deadline, connection_.GetPathDegradingAlarm()->deadline());

   // Now receive an ACK of the first packet. This should advance the path
   // degrading alarm's deadline since forward progress has been made.
   clock_.AdvanceTime(QuicTime::Delta::FromMilliseconds(5));
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
   EXPECT_CALL(*send_algorithm_, OnCongestionEvent(true, _, _, _, _));
   QuicAckFrame frame =
       InitAckFrame({{QuicPacketNumber(1u), QuicPacketNumber(2u)}});
   ProcessAckPacket(&frame);
   EXPECT_TRUE(connection_.GetPathDegradingAlarm()->IsSet());
   // Check the deadline of the path degrading alarm.
   delay = QuicConnectionPeer::GetSentPacketManager(&connection_)
               ->GetPathDegradingDelay();
   EXPECT_EQ(delay, connection_.GetPathDegradingAlarm()->deadline() -
                        clock_.ApproximateNow());

   // Advance time to the path degrading alarm's deadline and simulate
   // firing the alarm.
   clock_.AdvanceTime(delay);
   EXPECT_CALL(visitor_, OnPathDegrading()).Times(1);
   connection_.GetPathDegradingAlarm()->Fire();
   EXPECT_FALSE(connection_.GetPathDegradingAlarm()->IsSet());
   EXPECT_TRUE(connection_.IsPathDegrading());

   // Send a third packet. The path degrading alarm is no longer set but path
   // should still be marked as degrading.
   clock_.AdvanceTime(QuicTime::Delta::FromMilliseconds(5));
   EXPECT_FALSE(connection_.GetPathDegradingAlarm()->IsSet());
   connection_.SendStreamDataWithString(1, data, offset, NO_FIN);
   offset += data_size;
   EXPECT_FALSE(connection_.GetPathDegradingAlarm()->IsSet());
   EXPECT_TRUE(connection_.IsPathDegrading());

   // Now receive an ACK of the second packet. This should unmark the path as
   // degrading. And will set a timer to detect new path degrading.
   clock_.AdvanceTime(QuicTime::Delta::FromMilliseconds(5));
   EXPECT_CALL(*send_algorithm_, OnCongestionEvent(true, _, _, _, _));
   frame = InitAckFrame({{QuicPacketNumber(2), QuicPacketNumber(3)}});
   ProcessAckPacket(&frame);
   EXPECT_FALSE(connection_.IsPathDegrading());
   EXPECT_TRUE(connection_.GetPathDegradingAlarm()->IsSet());
 }

 TEST_P(QuicConnectionTest, NoPathDegradingOnServer) {
   if (connection_.SupportsMultiplePacketNumberSpaces()) {
     return;
   }
   set_perspective(Perspective::IS_SERVER);
   QuicPacketCreatorPeer::SetSendVersionInPacket(creator_, false);

   EXPECT_FALSE(connection_.IsPathDegrading());
   EXPECT_FALSE(connection_.GetPathDegradingAlarm()->IsSet());

   // Send data.
   const char data[] = "data";
   connection_.SendStreamDataWithString(1, data, 0, NO_FIN);
   EXPECT_FALSE(connection_.IsPathDegrading());
   EXPECT_FALSE(connection_.GetPathDegradingAlarm()->IsSet());

   // Ack data.
   clock_.AdvanceTime(QuicTime::Delta::FromMilliseconds(5));
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
   EXPECT_CALL(*send_algorithm_, OnCongestionEvent(true, _, _, _, _));
   QuicAckFrame frame =
       InitAckFrame({{QuicPacketNumber(1u), QuicPacketNumber(2u)}});
   ProcessAckPacket(&frame);
   EXPECT_FALSE(connection_.IsPathDegrading());
   EXPECT_FALSE(connection_.GetPathDegradingAlarm()->IsSet());
 }

 TEST_P(QuicConnectionTest, NoPathDegradingAfterSendingAck) {
   if (connection_.SupportsMultiplePacketNumberSpaces()) {
     return;
   }
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
   EXPECT_CALL(visitor_, OnStreamFrame(_)).Times(1);
   ProcessDataPacket(1);
   SendAckPacketToPeer();
   EXPECT_FALSE(connection_.sent_packet_manager().unacked_packets().empty());
   EXPECT_FALSE(connection_.sent_packet_manager().HasInFlightPackets());
   EXPECT_FALSE(connection_.IsPathDegrading());
   EXPECT_FALSE(connection_.GetPathDegradingAlarm()->IsSet());
 }

 TEST_P(QuicConnectionTest, MultipleCallsToCloseConnection) {
   // Verifies that multiple calls to CloseConnection do not
   // result in multiple attempts to close the connection - it will be marked as
   // disconnected after the first call.
   EXPECT_CALL(visitor_, OnConnectionClosed(_, _)).Times(1);
   connection_.CloseConnection(QUIC_NO_ERROR, "no reason",
                               ConnectionCloseBehavior::SILENT_CLOSE);
   connection_.CloseConnection(QUIC_NO_ERROR, "no reason",
                               ConnectionCloseBehavior::SILENT_CLOSE);
 }

 TEST_P(QuicConnectionTest, ServerReceivesChloOnNonCryptoStream) {
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));

   set_perspective(Perspective::IS_SERVER);
   QuicPacketCreatorPeer::SetSendVersionInPacket(creator_, false);

   CryptoHandshakeMessage message;
   CryptoFramer framer;
   message.set_tag(kCHLO);
   std::unique_ptr<QuicData> data = framer.ConstructHandshakeMessage(message);
   frame1_.stream_id = 10;
   frame1_.data_buffer = data->data();
   frame1_.data_length = data->length();

   EXPECT_CALL(visitor_,
               OnConnectionClosed(_, ConnectionCloseSource::FROM_SELF));
   ForceProcessFramePacket(QuicFrame(frame1_));
   TestConnectionCloseQuicErrorCode(QUIC_MAYBE_CORRUPTED_MEMORY);
 }

 TEST_P(QuicConnectionTest, ClientReceivesRejOnNonCryptoStream) {
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));

   CryptoHandshakeMessage message;
   CryptoFramer framer;
   message.set_tag(kREJ);
   std::unique_ptr<QuicData> data = framer.ConstructHandshakeMessage(message);
   frame1_.stream_id = 10;
   frame1_.data_buffer = data->data();
   frame1_.data_length = data->length();

   EXPECT_CALL(visitor_,
               OnConnectionClosed(_, ConnectionCloseSource::FROM_SELF));
   ForceProcessFramePacket(QuicFrame(frame1_));
   TestConnectionCloseQuicErrorCode(QUIC_MAYBE_CORRUPTED_MEMORY);
 }

 TEST_P(QuicConnectionTest, CloseConnectionOnPacketTooLarge) {
   SimulateNextPacketTooLarge();
   // A connection close packet is sent
   EXPECT_CALL(visitor_, OnConnectionClosed(_, ConnectionCloseSource::FROM_SELF))
       .Times(1);
   connection_.SendStreamDataWithString(3, "foo", 0, NO_FIN);
   TestConnectionCloseQuicErrorCode(QUIC_PACKET_WRITE_ERROR);
 }

 TEST_P(QuicConnectionTest, AlwaysGetPacketTooLarge) {
   // Test even we always get packet too large, we do not infinitely try to send
   // close packet.
   AlwaysGetPacketTooLarge();
   EXPECT_CALL(visitor_, OnConnectionClosed(_, ConnectionCloseSource::FROM_SELF))
       .Times(1);
   connection_.SendStreamDataWithString(3, "foo", 0, NO_FIN);
   TestConnectionCloseQuicErrorCode(QUIC_PACKET_WRITE_ERROR);
 }

 TEST_P(QuicConnectionTest, CloseConnectionOnQueuedWriteError) {
   // Regression test for crbug.com/979507.
   //
   // If we get a write error when writing queued packets, we should attempt to
   // send a connection close packet, but if sending that fails, it shouldn't get
   // queued.

   // Queue a packet to write.
   BlockOnNextWrite();
   connection_.SendStreamDataWithString(3, "foo", 0, NO_FIN);
   EXPECT_EQ(1u, connection_.NumQueuedPackets());

   // Configure writer to always fail.
   AlwaysGetPacketTooLarge();

   // Expect that we attempt to close the connection exactly once.
   EXPECT_CALL(visitor_, OnConnectionClosed(_, ConnectionCloseSource::FROM_SELF))
       .Times(1);

   // Unblock the writes and actually send.
   writer_->SetWritable();
   connection_.OnCanWrite();
   EXPECT_EQ(0u, connection_.NumQueuedPackets());

   TestConnectionCloseQuicErrorCode(QUIC_PACKET_WRITE_ERROR);
 }

 // Verify that if connection has no outstanding data, it notifies the send
 // algorithm after the write.
 TEST_P(QuicConnectionTest, SendDataAndBecomeApplicationLimited) {
   EXPECT_CALL(*send_algorithm_, OnApplicationLimited(_)).Times(1);
   {
     InSequence seq;
     EXPECT_CALL(visitor_, WillingAndAbleToWrite()).WillRepeatedly(Return(true));
     EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _));
     EXPECT_CALL(visitor_, WillingAndAbleToWrite())
         .WillRepeatedly(Return(false));
   }

   connection_.SendStreamData3();
 }

 // Verify that the connection does not become app-limited if there is
 // outstanding data to send after the write.
 TEST_P(QuicConnectionTest, NotBecomeApplicationLimitedIfMoreDataAvailable) {
   EXPECT_CALL(*send_algorithm_, OnApplicationLimited(_)).Times(0);
   {
     InSequence seq;
     EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _));
     EXPECT_CALL(visitor_, WillingAndAbleToWrite()).WillRepeatedly(Return(true));
   }

   connection_.SendStreamData3();
 }

 // Verify that the connection does not become app-limited after blocked write
 // even if there is outstanding data to send after the write.
 TEST_P(QuicConnectionTest, NotBecomeApplicationLimitedDueToWriteBlock) {
   EXPECT_CALL(*send_algorithm_, OnApplicationLimited(_)).Times(0);
   EXPECT_CALL(visitor_, WillingAndAbleToWrite()).WillRepeatedly(Return(true));
   BlockOnNextWrite();

   if (GetQuicReloadableFlag(quic_treat_queued_packets_as_sent)) {
     EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(1);
   } else {
     EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(0);
   }
   connection_.SendStreamData3();

   // Now unblock the writer, become congestion control blocked,
   // and ensure we become app-limited after writing.
   writer_->SetWritable();
   CongestionBlockWrites();
   EXPECT_CALL(visitor_, WillingAndAbleToWrite()).WillRepeatedly(Return(false));
   if (GetQuicReloadableFlag(quic_treat_queued_packets_as_sent)) {
     EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(0);
   } else {
     EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(1);
   }
   EXPECT_CALL(*send_algorithm_, OnApplicationLimited(_)).Times(1);
   connection_.OnCanWrite();
 }

 // Test the mode in which the link is filled up with probing retransmissions if
 // the connection becomes application-limited.
 TEST_P(QuicConnectionTest, SendDataWhenApplicationLimited) {
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
   EXPECT_CALL(*send_algorithm_, ShouldSendProbingPacket())
       .WillRepeatedly(Return(true));
   {
     InSequence seq;
     EXPECT_CALL(visitor_, WillingAndAbleToWrite()).WillRepeatedly(Return(true));
     EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _));
     EXPECT_CALL(visitor_, WillingAndAbleToWrite())
         .WillRepeatedly(Return(false));
   }
   EXPECT_CALL(visitor_, SendProbingData()).WillRepeatedly([this] {
     return connection_.sent_packet_manager().MaybeRetransmitOldestPacket(
         PROBING_RETRANSMISSION);
   });
   // Fix congestion window to be 20,000 bytes.
   EXPECT_CALL(*send_algorithm_, CanSend(Ge(20000u)))
       .WillRepeatedly(Return(false));
   EXPECT_CALL(*send_algorithm_, CanSend(Lt(20000u)))
       .WillRepeatedly(Return(true));

   EXPECT_CALL(*send_algorithm_, OnApplicationLimited(_)).Times(0);
   ASSERT_EQ(0u, connection_.GetStats().packets_sent);
   connection_.set_fill_up_link_during_probing(true);
   connection_.OnHandshakeComplete();
   connection_.SendStreamData3();

   // We expect a lot of packets from a 20 kbyte window.
   EXPECT_GT(connection_.GetStats().packets_sent, 10u);
   // Ensure that the packets are padded.
   QuicByteCount average_packet_size =
       connection_.GetStats().bytes_sent / connection_.GetStats().packets_sent;
   EXPECT_GT(average_packet_size, 1000u);

   // Acknowledge all packets sent, except for the last one.
   QuicAckFrame ack = InitAckFrame(
       connection_.sent_packet_manager().GetLargestSentPacket() - 1);
   EXPECT_CALL(*loss_algorithm_, DetectLosses(_, _, _, _, _, _));
   EXPECT_CALL(*send_algorithm_, OnCongestionEvent(true, _, _, _, _));

   // Ensure that since we no longer have retransmittable bytes in flight, this
   // will not cause any responses to be sent.
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(0);
   EXPECT_CALL(*send_algorithm_, OnApplicationLimited(_)).Times(1);
   ProcessAckPacket(&ack);
 }

 TEST_P(QuicConnectionTest, DonotForceSendingAckOnPacketTooLarge) {
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
   // Send an ack by simulating delayed ack alarm firing.
   ProcessPacket(1);
   QuicAlarm* ack_alarm = QuicConnectionPeer::GetAckAlarm(&connection_);
   EXPECT_TRUE(ack_alarm->IsSet());
   connection_.GetAckAlarm()->Fire();
   // Simulate data packet causes write error.
   EXPECT_CALL(visitor_, OnConnectionClosed(_, _));
   SimulateNextPacketTooLarge();
   connection_.SendStreamDataWithString(3, "foo", 0, NO_FIN);
   EXPECT_EQ(1u, writer_->frame_count());
   EXPECT_FALSE(writer_->connection_close_frames().empty());
   // Ack frame is not bundled in connection close packet.
   EXPECT_TRUE(writer_->ack_frames().empty());
   TestConnectionCloseQuicErrorCode(QUIC_PACKET_WRITE_ERROR);
 }

 // Regression test for b/63620844.
 TEST_P(QuicConnectionTest, FailedToWriteHandshakePacket) {
   SimulateNextPacketTooLarge();
   EXPECT_CALL(visitor_, OnConnectionClosed(_, ConnectionCloseSource::FROM_SELF))
       .Times(1);

   connection_.SendCryptoStreamData();
   TestConnectionCloseQuicErrorCode(QUIC_PACKET_WRITE_ERROR);
 }

 TEST_P(QuicConnectionTest, MaxPacingRate) {
   EXPECT_EQ(0, connection_.MaxPacingRate().ToBytesPerSecond());
   connection_.SetMaxPacingRate(QuicBandwidth::FromBytesPerSecond(100));
   EXPECT_EQ(100, connection_.MaxPacingRate().ToBytesPerSecond());
 }

 TEST_P(QuicConnectionTest, ClientAlwaysSendConnectionId) {
   EXPECT_EQ(Perspective::IS_CLIENT, connection_.perspective());
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(1);
   connection_.SendStreamDataWithString(3, "foo", 0, NO_FIN);
   EXPECT_EQ(CONNECTION_ID_PRESENT,
             writer_->last_packet_header().destination_connection_id_included);

   EXPECT_CALL(*send_algorithm_, SetFromConfig(_, _));
   QuicConfig config;
   QuicConfigPeer::SetReceivedBytesForConnectionId(&config, 0);
   connection_.SetFromConfig(config);

   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(1);
   connection_.SendStreamDataWithString(3, "bar", 3, NO_FIN);
   // Verify connection id is still sent in the packet.
   EXPECT_EQ(CONNECTION_ID_PRESENT,
             writer_->last_packet_header().destination_connection_id_included);
 }

 TEST_P(QuicConnectionTest, SendProbingRetransmissions) {
   MockQuicConnectionDebugVisitor debug_visitor;
   connection_.set_debug_visitor(&debug_visitor);

   const QuicStreamId stream_id = 2;
   QuicPacketNumber last_packet;
   SendStreamDataToPeer(stream_id, "foo", 0, NO_FIN, &last_packet);
   SendStreamDataToPeer(stream_id, "bar", 3, NO_FIN, &last_packet);
   SendStreamDataToPeer(stream_id, "test", 6, NO_FIN, &last_packet);

   const QuicByteCount old_bytes_in_flight =
       connection_.sent_packet_manager().GetBytesInFlight();

   // Allow 9 probing retransmissions to be sent.
   {
     InSequence seq;
     EXPECT_CALL(*send_algorithm_, CanSend(_))
         .Times(9 * 2)
         .WillRepeatedly(Return(true));
     EXPECT_CALL(*send_algorithm_, CanSend(_)).WillOnce(Return(false));
   }
   // Expect them retransmitted in cyclic order (foo, bar, test, foo, bar...).
   QuicPacketCount sent_count = 0;
   EXPECT_CALL(debug_visitor, OnPacketSent(_, _, _, _))
       .WillRepeatedly(Invoke([this, &sent_count](const SerializedPacket&,
                                                  QuicPacketNumber,
                                                  TransmissionType, QuicTime) {
         ASSERT_EQ(1u, writer_->stream_frames().size());
         // Identify the frames by stream offset (0, 3, 6, 0, 3...).
         EXPECT_EQ(3 * (sent_count % 3), writer_->stream_frames()[0]->offset);
         sent_count++;
       }));
   EXPECT_CALL(*send_algorithm_, ShouldSendProbingPacket())
       .WillRepeatedly(Return(true));
   EXPECT_CALL(visitor_, SendProbingData()).WillRepeatedly([this] {
     return connection_.sent_packet_manager().MaybeRetransmitOldestPacket(
         PROBING_RETRANSMISSION);
   });

   connection_.SendProbingRetransmissions();

   // Ensure that the in-flight has increased.
   const QuicByteCount new_bytes_in_flight =
       connection_.sent_packet_manager().GetBytesInFlight();
   EXPECT_GT(new_bytes_in_flight, old_bytes_in_flight);
 }

 // Ensure that SendProbingRetransmissions() does not retransmit anything when
 // there are no outstanding packets.
 TEST_P(QuicConnectionTest,
        SendProbingRetransmissionsFailsWhenNothingToRetransmit) {
   ASSERT_TRUE(connection_.sent_packet_manager().unacked_packets().empty());

   MockQuicConnectionDebugVisitor debug_visitor;
   connection_.set_debug_visitor(&debug_visitor);
   EXPECT_CALL(debug_visitor, OnPacketSent(_, _, _, _)).Times(0);
   EXPECT_CALL(*send_algorithm_, ShouldSendProbingPacket())
       .WillRepeatedly(Return(true));
   EXPECT_CALL(visitor_, SendProbingData()).WillRepeatedly([this] {
     return connection_.sent_packet_manager().MaybeRetransmitOldestPacket(
         PROBING_RETRANSMISSION);
   });

   connection_.SendProbingRetransmissions();
 }

 TEST_P(QuicConnectionTest, PingAfterLastRetransmittablePacketAcked) {
   const QuicTime::Delta retransmittable_on_wire_timeout =
       QuicTime::Delta::FromMilliseconds(50);
   connection_.set_retransmittable_on_wire_timeout(
       retransmittable_on_wire_timeout);

   EXPECT_TRUE(connection_.connected());
   EXPECT_CALL(visitor_, ShouldKeepConnectionAlive())
       .WillRepeatedly(Return(true));

   const char data[] = "data";
   size_t data_size = strlen(data);
   QuicStreamOffset offset = 0;

   // Advance 5ms, send a retransmittable packet to the peer.
   clock_.AdvanceTime(QuicTime::Delta::FromMilliseconds(5));
   EXPECT_FALSE(connection_.GetPingAlarm()->IsSet());
   connection_.SendStreamDataWithString(1, data, offset, NO_FIN);
   offset += data_size;
   EXPECT_TRUE(connection_.sent_packet_manager().HasInFlightPackets());
   // The ping alarm is set for the ping timeout, not the shorter
   // retransmittable_on_wire_timeout.
   EXPECT_TRUE(connection_.GetPingAlarm()->IsSet());
   QuicTime::Delta ping_delay = QuicTime::Delta::FromSeconds(kPingTimeoutSecs);
   EXPECT_EQ(ping_delay,
             connection_.GetPingAlarm()->deadline() - clock_.ApproximateNow());

   // Advance 5ms, send a second retransmittable packet to the peer.
   clock_.AdvanceTime(QuicTime::Delta::FromMilliseconds(5));
   EXPECT_TRUE(connection_.GetPingAlarm()->IsSet());
   connection_.SendStreamDataWithString(1, data, offset, NO_FIN);
   offset += data_size;
   EXPECT_TRUE(connection_.GetPingAlarm()->IsSet());

   // Now receive an ACK of the first packet. This should not set the
   // retransmittable-on-wire alarm since packet 2 is still on the wire.
   clock_.AdvanceTime(QuicTime::Delta::FromMilliseconds(5));
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
   EXPECT_CALL(*send_algorithm_, OnCongestionEvent(true, _, _, _, _));
   QuicAckFrame frame =
       InitAckFrame({{QuicPacketNumber(1), QuicPacketNumber(2)}});
   ProcessAckPacket(&frame);
   EXPECT_TRUE(connection_.sent_packet_manager().HasInFlightPackets());
   // The ping alarm is set for the ping timeout, not the shorter
   // retransmittable_on_wire_timeout.
   EXPECT_TRUE(connection_.GetPingAlarm()->IsSet());
   // The ping alarm has a 1 second granularity, and the clock has been advanced
   // 10ms since it was originally set.
   EXPECT_EQ(ping_delay - QuicTime::Delta::FromMilliseconds(10),
             connection_.GetPingAlarm()->deadline() - clock_.ApproximateNow());

   // Now receive an ACK of the second packet. This should set the
   // retransmittable-on-wire alarm now that no retransmittable packets are on
   // the wire.
   clock_.AdvanceTime(QuicTime::Delta::FromMilliseconds(5));
   EXPECT_CALL(*send_algorithm_, OnCongestionEvent(true, _, _, _, _));
   frame = InitAckFrame({{QuicPacketNumber(2), QuicPacketNumber(3)}});
   ProcessAckPacket(&frame);
   EXPECT_TRUE(connection_.GetPingAlarm()->IsSet());
   EXPECT_EQ(retransmittable_on_wire_timeout,
             connection_.GetPingAlarm()->deadline() - clock_.ApproximateNow());

   // Now receive a duplicate ACK of the second packet. This should not update
   // the ping alarm.
   QuicTime prev_deadline = connection_.GetPingAlarm()->deadline();
   clock_.AdvanceTime(QuicTime::Delta::FromMilliseconds(5));
   frame = InitAckFrame({{QuicPacketNumber(2), QuicPacketNumber(3)}});
   ProcessAckPacket(&frame);
   EXPECT_TRUE(connection_.GetPingAlarm()->IsSet());
   EXPECT_EQ(prev_deadline, connection_.GetPingAlarm()->deadline());

   // Now receive a non-ACK packet.  This should not update the ping alarm.
   prev_deadline = connection_.GetPingAlarm()->deadline();
   clock_.AdvanceTime(QuicTime::Delta::FromMilliseconds(5));
   ProcessPacket(4);
   EXPECT_TRUE(connection_.GetPingAlarm()->IsSet());
   EXPECT_EQ(prev_deadline, connection_.GetPingAlarm()->deadline());

   // Simulate the alarm firing and check that a PING is sent.
   EXPECT_CALL(visitor_, SendPing()).WillOnce(Invoke([this]() {
     connection_.SendControlFrame(QuicFrame(QuicPingFrame(1)));
   }));
   connection_.GetPingAlarm()->Fire();
   size_t padding_frame_count = writer_->padding_frames().size();
   if (GetParam().no_stop_waiting) {
     EXPECT_EQ(padding_frame_count + 2u, writer_->frame_count());
   } else {
     EXPECT_EQ(padding_frame_count + 3u, writer_->frame_count());
   }
   ASSERT_EQ(1u, writer_->ping_frames().size());
 }

 TEST_P(QuicConnectionTest, NoPingIfRetransmittablePacketSent) {
   const QuicTime::Delta retransmittable_on_wire_timeout =
       QuicTime::Delta::FromMilliseconds(50);
   connection_.set_retransmittable_on_wire_timeout(
       retransmittable_on_wire_timeout);

   EXPECT_TRUE(connection_.connected());
   EXPECT_CALL(visitor_, ShouldKeepConnectionAlive())
       .WillRepeatedly(Return(true));

   const char data[] = "data";
   size_t data_size = strlen(data);
   QuicStreamOffset offset = 0;

   // Advance 5ms, send a retransmittable packet to the peer.
   clock_.AdvanceTime(QuicTime::Delta::FromMilliseconds(5));
   EXPECT_FALSE(connection_.GetPingAlarm()->IsSet());
   connection_.SendStreamDataWithString(1, data, offset, NO_FIN);
   offset += data_size;
   EXPECT_TRUE(connection_.sent_packet_manager().HasInFlightPackets());
   // The ping alarm is set for the ping timeout, not the shorter
   // retransmittable_on_wire_timeout.
   EXPECT_TRUE(connection_.GetPingAlarm()->IsSet());
   QuicTime::Delta ping_delay = QuicTime::Delta::FromSeconds(kPingTimeoutSecs);
   EXPECT_EQ(ping_delay,
             connection_.GetPingAlarm()->deadline() - clock_.ApproximateNow());

   // Now receive an ACK of the first packet. This should set the
   // retransmittable-on-wire alarm now that no retransmittable packets are on
   // the wire.
   clock_.AdvanceTime(QuicTime::Delta::FromMilliseconds(5));
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
   EXPECT_CALL(*send_algorithm_, OnCongestionEvent(true, _, _, _, _));
   QuicAckFrame frame =
       InitAckFrame({{QuicPacketNumber(1), QuicPacketNumber(2)}});
   ProcessAckPacket(&frame);
   EXPECT_TRUE(connection_.GetPingAlarm()->IsSet());
   EXPECT_EQ(retransmittable_on_wire_timeout,
             connection_.GetPingAlarm()->deadline() - clock_.ApproximateNow());

   // Before the alarm fires, send another retransmittable packet. This should
   // cancel the retransmittable-on-wire alarm since now there's a
   // retransmittable packet on the wire.
   connection_.SendStreamDataWithString(1, data, offset, NO_FIN);
   offset += data_size;
   EXPECT_TRUE(connection_.GetPingAlarm()->IsSet());

   // Now receive an ACK of the second packet. This should set the
   // retransmittable-on-wire alarm now that no retransmittable packets are on
   // the wire.
   clock_.AdvanceTime(QuicTime::Delta::FromMilliseconds(5));
   EXPECT_CALL(*send_algorithm_, OnCongestionEvent(true, _, _, _, _));
   frame = InitAckFrame({{QuicPacketNumber(2), QuicPacketNumber(3)}});
   ProcessAckPacket(&frame);
   EXPECT_TRUE(connection_.GetPingAlarm()->IsSet());
   EXPECT_EQ(retransmittable_on_wire_timeout,
             connection_.GetPingAlarm()->deadline() - clock_.ApproximateNow());

   // Simulate the alarm firing and check that a PING is sent.
   writer_->Reset();
   EXPECT_CALL(visitor_, SendPing()).WillOnce(Invoke([this]() {
     connection_.SendControlFrame(QuicFrame(QuicPingFrame(1)));
   }));
   connection_.GetPingAlarm()->Fire();
   size_t padding_frame_count = writer_->padding_frames().size();
   if (GetParam().no_stop_waiting) {
     if (GetQuicReloadableFlag(quic_simplify_stop_waiting)) {
       // Do not ACK acks.
       EXPECT_EQ(padding_frame_count + 1u, writer_->frame_count());
     } else {
       EXPECT_EQ(padding_frame_count + 2u, writer_->frame_count());
     }
   } else {
     EXPECT_EQ(padding_frame_count + 3u, writer_->frame_count());
   }
   ASSERT_EQ(1u, writer_->ping_frames().size());
 }

 TEST_P(QuicConnectionTest, OnForwardProgressConfirmed) {
   EXPECT_CALL(visitor_, OnForwardProgressConfirmed()).Times(Exactly(0));
   EXPECT_TRUE(connection_.connected());

   const char data[] = "data";
   size_t data_size = strlen(data);
   QuicStreamOffset offset = 0;

   // Send two packets.
   connection_.SendStreamDataWithString(1, data, offset, NO_FIN);
   offset += data_size;
   connection_.SendStreamDataWithString(1, data, offset, NO_FIN);
   offset += data_size;

   // Ack packet 1. This increases the largest_acked to 1, so
   // OnForwardProgressConfirmed() should be called
   clock_.AdvanceTime(QuicTime::Delta::FromMilliseconds(5));
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
   EXPECT_CALL(*send_algorithm_, OnCongestionEvent(true, _, _, _, _));
   EXPECT_CALL(visitor_, OnForwardProgressConfirmed());
   QuicAckFrame frame =
       InitAckFrame({{QuicPacketNumber(1), QuicPacketNumber(2)}});
   ProcessAckPacket(&frame);

   // Ack packet 1 again. largest_acked remains at 1, so
   // OnForwardProgressConfirmed() should not be called.
   clock_.AdvanceTime(QuicTime::Delta::FromMilliseconds(5));
   frame = InitAckFrame({{QuicPacketNumber(1), QuicPacketNumber(2)}});
   ProcessAckPacket(&frame);

   // Ack packet 2. This increases the largest_acked to 2, so
   // OnForwardProgressConfirmed() should be called.
   clock_.AdvanceTime(QuicTime::Delta::FromMilliseconds(5));
   EXPECT_CALL(*send_algorithm_, OnCongestionEvent(true, _, _, _, _));
   EXPECT_CALL(visitor_, OnForwardProgressConfirmed());
   frame = InitAckFrame({{QuicPacketNumber(2), QuicPacketNumber(3)}});
   ProcessAckPacket(&frame);
 }

 TEST_P(QuicConnectionTest, ValidStatelessResetToken) {
   const QuicUint128 kTestToken = 1010101;
   const QuicUint128 kWrongTestToken = 1010100;
   QuicConfig config;
   // No token has been received.
   EXPECT_FALSE(connection_.IsValidStatelessResetToken(kTestToken));

   EXPECT_CALL(*send_algorithm_, SetFromConfig(_, _)).Times(2);
   // Token is different from received token.
   QuicConfigPeer::SetReceivedStatelessResetToken(&config, kTestToken);
   connection_.SetFromConfig(config);
   EXPECT_FALSE(connection_.IsValidStatelessResetToken(kWrongTestToken));

   QuicConfigPeer::SetReceivedStatelessResetToken(&config, kTestToken);
   connection_.SetFromConfig(config);
   EXPECT_TRUE(connection_.IsValidStatelessResetToken(kTestToken));
 }

 TEST_P(QuicConnectionTest, WriteBlockedWithInvalidAck) {
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
   if (GetQuicReloadableFlag(quic_treat_queued_packets_as_sent)) {
     EXPECT_CALL(visitor_, OnConnectionClosed(_, _)).Times(0);
   } else {
     EXPECT_CALL(visitor_, OnConnectionClosed(_, _))
         .WillOnce(Invoke(this, &QuicConnectionTest::SaveConnectionCloseFrame));
   }
   BlockOnNextWrite();
   if (GetQuicReloadableFlag(quic_treat_queued_packets_as_sent)) {
     EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(1);
   } else {
     EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(0);
   }
   connection_.SendStreamDataWithString(5, "foo", 0, FIN);
   // This causes connection to be closed because packet 1 has not been sent yet.
   QuicAckFrame frame = InitAckFrame(1);
   if (GetQuicReloadableFlag(quic_treat_queued_packets_as_sent)) {
     EXPECT_CALL(*send_algorithm_, OnCongestionEvent(_, _, _, _, _));
   }
   ProcessAckPacket(1, &frame);
   if (GetQuicReloadableFlag(quic_treat_queued_packets_as_sent)) {
     EXPECT_EQ(0, connection_close_frame_count_);
   } else {
     EXPECT_EQ(1, connection_close_frame_count_);
     EXPECT_EQ(QUIC_INVALID_ACK_DATA,
               saved_connection_close_frame_.quic_error_code);
   }
 }

 TEST_P(QuicConnectionTest, SendMessage) {
   if (!VersionSupportsMessageFrames(connection_.transport_version())) {
     return;
   }
   std::string message(connection_.GetCurrentLargestMessagePayload() * 2, 'a');
   QuicStringPiece message_data(message);
   QuicMemSliceStorage storage(nullptr, 0, nullptr, 0);
   {
     QuicConnection::ScopedPacketFlusher flusher(&connection_);
     connection_.SendStreamData3();
     // Send a message which cannot fit into current open packet, and 2 packets
     // get sent, one contains stream frame, and the other only contains the
     // message frame.
     EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(2);
     EXPECT_EQ(
         MESSAGE_STATUS_SUCCESS,
         connection_.SendMessage(
             1, MakeSpan(connection_.helper()->GetStreamSendBufferAllocator(),
                         QuicStringPiece(
                             message_data.data(),
                             connection_.GetCurrentLargestMessagePayload()),
                         &storage)));
   }
   // Fail to send a message if connection is congestion control blocked.
   EXPECT_CALL(*send_algorithm_, CanSend(_)).WillOnce(Return(false));
   EXPECT_EQ(
       MESSAGE_STATUS_BLOCKED,
       connection_.SendMessage(
           2, MakeSpan(connection_.helper()->GetStreamSendBufferAllocator(),
                       "message", &storage)));

   // Always fail to send a message which cannot fit into one packet.
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(0);
   EXPECT_EQ(
       MESSAGE_STATUS_TOO_LARGE,
       connection_.SendMessage(
           3, MakeSpan(connection_.helper()->GetStreamSendBufferAllocator(),
                       QuicStringPiece(
                           message_data.data(),
                           connection_.GetCurrentLargestMessagePayload() + 1),
                       &storage)));
 }

 // Test to check that the path challenge/path response logic works
 // correctly. This test is only for version-99
 TEST_P(QuicConnectionTest, PathChallengeResponse) {
   if (!VersionHasIetfQuicFrames(connection_.version().transport_version)) {
     return;
   }
   // First check if we can probe from server to client and back
   set_perspective(Perspective::IS_SERVER);
   QuicPacketCreatorPeer::SetSendVersionInPacket(creator_, false);

   // Create and send the probe request (PATH_CHALLENGE frame).
   // SendConnectivityProbingPacket ends up calling
   // TestPacketWriter::WritePacket() which in turns receives and parses the
   // packet by calling framer_.ProcessPacket() -- which in turn calls
   // SimpleQuicFramer::OnPathChallengeFrame(). SimpleQuicFramer saves
   // the packet in writer_->path_challenge_frames()
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(1);
   connection_.SendConnectivityProbingPacket(writer_.get(),
                                             connection_.peer_address());
   // Save the random contents of the challenge for later comparison to the
   // response.
   ASSERT_GE(writer_->path_challenge_frames().size(), 1u);
   QuicPathFrameBuffer challenge_data =
       writer_->path_challenge_frames().front().data_buffer;

   // Normally, QuicConnection::OnPathChallengeFrame and OnPaddingFrame would be
   // called and it will perform actions to ensure that the rest of the protocol
   // is performed (specifically, call UpdatePacketContent to say that this is a
   // path challenge so that when QuicConnection::OnPacketComplete is called
   // (again, out of the framer), the response is generated).  Simulate those
   // calls so that the right internal state is set up for generating
   // the response.
   EXPECT_TRUE(connection_.OnPathChallengeFrame(
       writer_->path_challenge_frames().front()));
   EXPECT_TRUE(connection_.OnPaddingFrame(writer_->padding_frames().front()));
   // Cause the response to be created and sent. Result is that the response
   // should be stashed in writer's path_response_frames.
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(1);
   connection_.SendConnectivityProbingResponsePacket(connection_.peer_address());

   // The final check is to ensure that the random data in the response matches
   // the random data from the challenge.
   EXPECT_EQ(0, memcmp(&challenge_data,
                       &(writer_->path_response_frames().front().data_buffer),
                       sizeof(challenge_data)));
 }

 // Regression test for b/110259444
 TEST_P(QuicConnectionTest, DoNotScheduleSpuriousAckAlarm) {
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
   EXPECT_CALL(visitor_, OnWriteBlocked()).Times(AtLeast(1));
   writer_->SetWriteBlocked();

   ProcessPacket(1);
   QuicAlarm* ack_alarm = QuicConnectionPeer::GetAckAlarm(&connection_);
   // Verify ack alarm is set.
   EXPECT_TRUE(ack_alarm->IsSet());
   // Fire the ack alarm, verify no packet is sent because the writer is blocked.
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(0);
   connection_.GetAckAlarm()->Fire();

   writer_->SetWritable();
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(1);
   ProcessPacket(2);
   // Verify ack alarm is not set.
   EXPECT_FALSE(ack_alarm->IsSet());
 }

 TEST_P(QuicConnectionTest, DisablePacingOffloadConnectionOptions) {
   EXPECT_FALSE(QuicConnectionPeer::SupportsReleaseTime(&connection_));
   writer_->set_supports_release_time(true);
   QuicConfig config;
   EXPECT_CALL(*send_algorithm_, SetFromConfig(_, _));
   connection_.SetFromConfig(config);
   EXPECT_TRUE(QuicConnectionPeer::SupportsReleaseTime(&connection_));

   QuicTagVector connection_options;
   connection_options.push_back(kNPCO);
   config.SetConnectionOptionsToSend(connection_options);
   EXPECT_CALL(*send_algorithm_, SetFromConfig(_, _));
   connection_.SetFromConfig(config);
   // Verify pacing offload is disabled.
   EXPECT_FALSE(QuicConnectionPeer::SupportsReleaseTime(&connection_));
 }

 // Regression test for b/110259444
 // Get a path response without having issued a path challenge...
 TEST_P(QuicConnectionTest, OrphanPathResponse) {
   QuicPathFrameBuffer data = {{0, 1, 2, 3, 4, 5, 6, 7}};

   QuicPathResponseFrame frame(99, data);
   EXPECT_TRUE(connection_.OnPathResponseFrame(frame));
   // If PATH_RESPONSE was accepted (payload matches the payload saved
   // in QuicConnection::transmitted_connectivity_probe_payload_) then
   // current_packet_content_ would be set to FIRST_FRAME_IS_PING.
   // Since this PATH_RESPONSE does not match, current_packet_content_
   // must not be FIRST_FRAME_IS_PING.
   EXPECT_NE(QuicConnection::FIRST_FRAME_IS_PING,
             QuicConnectionPeer::GetCurrentPacketContent(&connection_));
 }

 // Regression test for b/120791670
 TEST_P(QuicConnectionTest, StopProcessingGQuicPacketInIetfQuicConnection) {
   // This test mimics a problematic scenario where an IETF QUIC connection
   // receives a Google QUIC packet and continue processing it using Google QUIC
   // wire format.
   if (!VersionHasIetfInvariantHeader(version().transport_version)) {
     return;
   }
   set_perspective(Perspective::IS_SERVER);
   QuicFrame frame;
   if (QuicVersionUsesCryptoFrames(connection_.transport_version())) {
     frame = QuicFrame(&crypto_frame_);
     EXPECT_CALL(visitor_, OnCryptoFrame(_)).Times(1);
   } else {
     frame = QuicFrame(QuicStreamFrame(
         QuicUtils::GetCryptoStreamId(connection_.transport_version()), false,
         0u, QuicStringPiece()));
     EXPECT_CALL(visitor_, OnStreamFrame(_)).Times(1);
   }
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
   ProcessFramePacketWithAddresses(frame, kSelfAddress, kPeerAddress);

   // Let connection process a Google QUIC packet.
   peer_framer_.set_version_for_tests(
       ParsedQuicVersion(PROTOCOL_QUIC_CRYPTO, QUIC_VERSION_43));
   std::unique_ptr<QuicPacket> packet(
       ConstructDataPacket(2, !kHasStopWaiting, ENCRYPTION_INITIAL));
   char buffer[kMaxOutgoingPacketSize];
   size_t encrypted_length =
       peer_framer_.EncryptPayload(ENCRYPTION_INITIAL, QuicPacketNumber(2),
                                   *packet, buffer, kMaxOutgoingPacketSize);
   // Make sure no stream frame is processed.
   EXPECT_CALL(visitor_, OnStreamFrame(_)).Times(0);
   connection_.ProcessUdpPacket(
       kSelfAddress, kPeerAddress,
       QuicReceivedPacket(buffer, encrypted_length, clock_.Now(), false));

   EXPECT_EQ(2u, connection_.GetStats().packets_received);
   EXPECT_EQ(1u, connection_.GetStats().packets_processed);
 }

 TEST_P(QuicConnectionTest, AcceptPacketNumberZero) {
   if (!VersionHasIetfQuicFrames(version().transport_version)) {
     return;
   }
   // Set first_sending_packet_number to be 0 to allow successfully processing
   // acks which ack packet number 0.
   QuicFramerPeer::SetFirstSendingPacketNumber(writer_->framer()->framer(), 0);
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));

   ProcessPacket(0);
   EXPECT_EQ(QuicPacketNumber(0), LargestAcked(connection_.ack_frame()));
   EXPECT_EQ(1u, connection_.ack_frame().packets.NumIntervals());

   ProcessPacket(1);
   EXPECT_EQ(QuicPacketNumber(1), LargestAcked(connection_.ack_frame()));
   EXPECT_EQ(1u, connection_.ack_frame().packets.NumIntervals());

   ProcessPacket(2);
   EXPECT_EQ(QuicPacketNumber(2), LargestAcked(connection_.ack_frame()));
   EXPECT_EQ(1u, connection_.ack_frame().packets.NumIntervals());
 }

 TEST_P(QuicConnectionTest, MultiplePacketNumberSpacesBasicSending) {
   if (!connection_.SupportsMultiplePacketNumberSpaces()) {
     return;
   }
   use_tagging_decrypter();
   connection_.SetEncrypter(ENCRYPTION_INITIAL,
                            std::make_unique<TaggingEncrypter>(0x01));

   connection_.SendCryptoStreamData();
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
   EXPECT_CALL(*loss_algorithm_, DetectLosses(_, _, _, _, _, _));
   EXPECT_CALL(*send_algorithm_, OnCongestionEvent(true, _, _, _, _));
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(0);
   QuicAckFrame frame1 = InitAckFrame(1);
   // Received ACK for packet 1.
   ProcessFramePacketAtLevel(30, QuicFrame(&frame1), ENCRYPTION_INITIAL);

   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(4);
   connection_.SendApplicationDataAtLevel(ENCRYPTION_ZERO_RTT, 5, "data", 0,
                                          NO_FIN);
   connection_.SendApplicationDataAtLevel(ENCRYPTION_ZERO_RTT, 5, "data", 4,
                                          NO_FIN);
   connection_.SendApplicationDataAtLevel(ENCRYPTION_FORWARD_SECURE, 5, "data",
                                          8, NO_FIN);
   connection_.SendApplicationDataAtLevel(ENCRYPTION_FORWARD_SECURE, 5, "data",
                                          12, FIN);
   // Received ACK for packets 2, 4, 5.
   EXPECT_CALL(*loss_algorithm_, DetectLosses(_, _, _, _, _, _));
   EXPECT_CALL(*send_algorithm_, OnCongestionEvent(true, _, _, _, _));
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(0);
   QuicAckFrame frame2 =
       InitAckFrame({{QuicPacketNumber(2), QuicPacketNumber(3)},
                     {QuicPacketNumber(4), QuicPacketNumber(6)}});
   // Make sure although the same packet number is used, but they are in
   // different packet number spaces.
   ProcessFramePacketAtLevel(30, QuicFrame(&frame2), ENCRYPTION_FORWARD_SECURE);
 }

 TEST_P(QuicConnectionTest, PeerAcksPacketsInWrongPacketNumberSpace) {
   if (!connection_.SupportsMultiplePacketNumberSpaces()) {
     return;
   }
   use_tagging_decrypter();
   connection_.SetEncrypter(ENCRYPTION_INITIAL,
                            std::make_unique<TaggingEncrypter>(0x01));
   connection_.SetEncrypter(ENCRYPTION_FORWARD_SECURE,
                            std::make_unique<TaggingEncrypter>(0x01));

   connection_.SendCryptoStreamData();
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
   EXPECT_CALL(*loss_algorithm_, DetectLosses(_, _, _, _, _, _));
   EXPECT_CALL(*send_algorithm_, OnCongestionEvent(true, _, _, _, _));
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(0);
   QuicAckFrame frame1 = InitAckFrame(1);
   // Received ACK for packet 1.
   ProcessFramePacketAtLevel(30, QuicFrame(&frame1), ENCRYPTION_INITIAL);

   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(2);
   connection_.SendApplicationDataAtLevel(ENCRYPTION_ZERO_RTT, 5, "data", 0,
                                          NO_FIN);
   connection_.SendApplicationDataAtLevel(ENCRYPTION_ZERO_RTT, 5, "data", 4,
                                          NO_FIN);

   // Received ACK for packets 2 and 3 in wrong packet number space.
   QuicAckFrame invalid_ack =
       InitAckFrame({{QuicPacketNumber(2), QuicPacketNumber(4)}});
   EXPECT_CALL(visitor_,
               OnConnectionClosed(_, ConnectionCloseSource::FROM_SELF));
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(AtLeast(1));
   ProcessFramePacketAtLevel(300, QuicFrame(&invalid_ack), ENCRYPTION_INITIAL);
   TestConnectionCloseQuicErrorCode(QUIC_INVALID_ACK_DATA);
 }

 TEST_P(QuicConnectionTest, MultiplePacketNumberSpacesBasicReceiving) {
   if (!connection_.SupportsMultiplePacketNumberSpaces()) {
     return;
   }
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
   if (QuicVersionUsesCryptoFrames(connection_.transport_version())) {
     EXPECT_CALL(visitor_, OnCryptoFrame(_)).Times(AnyNumber());
   }
   EXPECT_CALL(visitor_, OnStreamFrame(_)).Times(AnyNumber());
   use_tagging_decrypter();
   // Receives packet 1000 in initial data.
   ProcessCryptoPacketAtLevel(1000, ENCRYPTION_INITIAL);
   EXPECT_TRUE(connection_.GetAckAlarm()->IsSet());
   peer_framer_.SetEncrypter(ENCRYPTION_ZERO_RTT,
                             std::make_unique<TaggingEncrypter>(0x02));
   SetDecrypter(ENCRYPTION_ZERO_RTT,
                std::make_unique<StrictTaggingDecrypter>(0x02));
   connection_.SetEncrypter(ENCRYPTION_INITIAL,
                            std::make_unique<TaggingEncrypter>(0x02));
   // Receives packet 1000 in application data.
   ProcessDataPacketAtLevel(1000, false, ENCRYPTION_ZERO_RTT);
   EXPECT_TRUE(connection_.GetAckAlarm()->IsSet());
   connection_.SendApplicationDataAtLevel(ENCRYPTION_ZERO_RTT, 5, "data", 0,
                                          NO_FIN);
   // Verify application data ACK gets bundled with outgoing data.
   EXPECT_EQ(2u, writer_->frame_count());
   // Make sure ACK alarm is still set because initial data is not ACKed.
   EXPECT_TRUE(connection_.GetAckAlarm()->IsSet());
   // Receive packet 1001 in application data.
   ProcessDataPacketAtLevel(1001, false, ENCRYPTION_ZERO_RTT);
   clock_.AdvanceTime(DefaultRetransmissionTime());
   // Simulates ACK alarm fires and verify two ACKs are flushed.
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(2);
   connection_.SetEncrypter(ENCRYPTION_FORWARD_SECURE,
                            std::make_unique<TaggingEncrypter>(0x02));
   connection_.GetAckAlarm()->Fire();
   EXPECT_FALSE(connection_.GetAckAlarm()->IsSet());
   // Receives more packets in application data.
   ProcessDataPacketAtLevel(1002, false, ENCRYPTION_ZERO_RTT);
   EXPECT_TRUE(connection_.GetAckAlarm()->IsSet());

   peer_framer_.SetEncrypter(ENCRYPTION_FORWARD_SECURE,
                             std::make_unique<TaggingEncrypter>(0x02));
   SetDecrypter(ENCRYPTION_FORWARD_SECURE,
                std::make_unique<StrictTaggingDecrypter>(0x02));
   // Verify zero rtt and forward secure packets get acked in the same packet.
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(1);
   ProcessDataPacket(1003);
   EXPECT_FALSE(connection_.GetAckAlarm()->IsSet());
 }

 TEST_P(QuicConnectionTest, CancelAckAlarmOnWriteBlocked) {
   if (!connection_.SupportsMultiplePacketNumberSpaces()) {
     return;
   }
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
   if (QuicVersionUsesCryptoFrames(connection_.transport_version())) {
     EXPECT_CALL(visitor_, OnCryptoFrame(_)).Times(AnyNumber());
   }
   EXPECT_CALL(visitor_, OnStreamFrame(_)).Times(AnyNumber());
   use_tagging_decrypter();
   // Receives packet 1000 in initial data.
   ProcessCryptoPacketAtLevel(1000, ENCRYPTION_INITIAL);
   EXPECT_TRUE(connection_.GetAckAlarm()->IsSet());
   peer_framer_.SetEncrypter(ENCRYPTION_ZERO_RTT,
                             std::make_unique<TaggingEncrypter>(0x02));
   SetDecrypter(ENCRYPTION_ZERO_RTT,
                std::make_unique<StrictTaggingDecrypter>(0x02));
   connection_.SetEncrypter(ENCRYPTION_INITIAL,
                            std::make_unique<TaggingEncrypter>(0x02));
   // Receives packet 1000 in application data.
   ProcessDataPacketAtLevel(1000, false, ENCRYPTION_ZERO_RTT);
   EXPECT_TRUE(connection_.GetAckAlarm()->IsSet());

   writer_->SetWriteBlocked();
   EXPECT_CALL(visitor_, OnWriteBlocked()).Times(AnyNumber());
   // Simulates ACK alarm fires and verify no ACK is flushed because of write
   // blocked.
   clock_.AdvanceTime(DefaultDelayedAckTime());
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(0);
   connection_.SetEncrypter(ENCRYPTION_FORWARD_SECURE,
                            std::make_unique<TaggingEncrypter>(0x02));
   connection_.GetAckAlarm()->Fire();
   // Verify ACK alarm is not set.
   EXPECT_FALSE(connection_.GetAckAlarm()->IsSet());

   writer_->SetWritable();
   // Verify 2 ACKs are sent when connection gets unblocked.
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(2);
   connection_.OnCanWrite();
   EXPECT_FALSE(connection_.GetAckAlarm()->IsSet());
 }

 // Make sure a packet received with the right client connection ID is processed.
 TEST_P(QuicConnectionTest, ValidClientConnectionId) {
   if (!framer_.version().SupportsClientConnectionIds()) {
     return;
   }
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
   connection_.set_client_connection_id(TestConnectionId(0x33));
   QuicPacketHeader header = ConstructPacketHeader(1, ENCRYPTION_FORWARD_SECURE);
   header.destination_connection_id = TestConnectionId(0x33);
   header.destination_connection_id_included = CONNECTION_ID_PRESENT;
   header.source_connection_id_included = CONNECTION_ID_ABSENT;
   QuicFrames frames;
   QuicPingFrame ping_frame;
   QuicPaddingFrame padding_frame;
   frames.push_back(QuicFrame(ping_frame));
   frames.push_back(QuicFrame(padding_frame));
   std::unique_ptr<QuicPacket> packet =
       BuildUnsizedDataPacket(&framer_, header, frames);
   char buffer[kMaxOutgoingPacketSize];
   size_t encrypted_length = peer_framer_.EncryptPayload(
       ENCRYPTION_FORWARD_SECURE, QuicPacketNumber(1), *packet, buffer,
       kMaxOutgoingPacketSize);
   QuicReceivedPacket received_packet(buffer, encrypted_length, clock_.Now(),
                                      false);
   EXPECT_EQ(0u, connection_.GetStats().packets_dropped);
   ProcessReceivedPacket(kSelfAddress, kPeerAddress, received_packet);
   EXPECT_EQ(0u, connection_.GetStats().packets_dropped);
 }

 // Make sure a packet received with a different client connection ID is dropped.
 TEST_P(QuicConnectionTest, InvalidClientConnectionId) {
   if (!framer_.version().SupportsClientConnectionIds()) {
     return;
   }
   connection_.set_client_connection_id(TestConnectionId(0x33));
   QuicPacketHeader header = ConstructPacketHeader(1, ENCRYPTION_FORWARD_SECURE);
   header.destination_connection_id = TestConnectionId(0xbad);
   header.destination_connection_id_included = CONNECTION_ID_PRESENT;
   header.source_connection_id_included = CONNECTION_ID_ABSENT;
   QuicFrames frames;
   QuicPingFrame ping_frame;
   QuicPaddingFrame padding_frame;
   frames.push_back(QuicFrame(ping_frame));
   frames.push_back(QuicFrame(padding_frame));
   std::unique_ptr<QuicPacket> packet =
       BuildUnsizedDataPacket(&framer_, header, frames);
   char buffer[kMaxOutgoingPacketSize];
   size_t encrypted_length = peer_framer_.EncryptPayload(
       ENCRYPTION_FORWARD_SECURE, QuicPacketNumber(1), *packet, buffer,
       kMaxOutgoingPacketSize);
   QuicReceivedPacket received_packet(buffer, encrypted_length, clock_.Now(),
                                      false);
   EXPECT_EQ(0u, connection_.GetStats().packets_dropped);
   ProcessReceivedPacket(kSelfAddress, kPeerAddress, received_packet);
   EXPECT_EQ(1u, connection_.GetStats().packets_dropped);
 }

 // Make sure the first packet received with a different client connection ID on
 // the server is processed and it changes the client connection ID.
 TEST_P(QuicConnectionTest, UpdateClientConnectionIdFromFirstPacket) {
   if (!framer_.version().SupportsClientConnectionIds()) {
     return;
   }
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
   set_perspective(Perspective::IS_SERVER);
   QuicPacketHeader header = ConstructPacketHeader(1, ENCRYPTION_INITIAL);
   header.source_connection_id = TestConnectionId(0x33);
   header.source_connection_id_included = CONNECTION_ID_PRESENT;
   QuicFrames frames;
   QuicPingFrame ping_frame;
   QuicPaddingFrame padding_frame;
   frames.push_back(QuicFrame(ping_frame));
   frames.push_back(QuicFrame(padding_frame));
   std::unique_ptr<QuicPacket> packet =
       BuildUnsizedDataPacket(&framer_, header, frames);
   char buffer[kMaxOutgoingPacketSize];
   size_t encrypted_length =
       peer_framer_.EncryptPayload(ENCRYPTION_INITIAL, QuicPacketNumber(1),
                                   *packet, buffer, kMaxOutgoingPacketSize);
   QuicReceivedPacket received_packet(buffer, encrypted_length, clock_.Now(),
                                      false);
   EXPECT_EQ(0u, connection_.GetStats().packets_dropped);
   ProcessReceivedPacket(kSelfAddress, kPeerAddress, received_packet);
   EXPECT_EQ(0u, connection_.GetStats().packets_dropped);
   EXPECT_EQ(TestConnectionId(0x33), connection_.client_connection_id());
 }

 // Regression test for b/134416344.
 TEST_P(QuicConnectionTest, CheckConnectedBeforeFlush) {
   // This test mimics a scenario where a connection processes 2 packets and the
   // 2nd packet contains connection close frame. When the 2nd flusher goes out
   // of scope, a delayed ACK is pending, and ACK alarm should not be scheduled
   // because connection is disconnected.
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
   EXPECT_CALL(visitor_, OnConnectionClosed(_, _));
   EXPECT_EQ(Perspective::IS_CLIENT, connection_.perspective());
   const QuicErrorCode kErrorCode = QUIC_INTERNAL_ERROR;
   std::unique_ptr<QuicConnectionCloseFrame> connection_close_frame(
       new QuicConnectionCloseFrame(connection_.transport_version(), kErrorCode,
                                    "",
                                    /*transport_close_frame_type=*/0));

   // Received 2 packets.
   QuicFrame frame;
   if (QuicVersionUsesCryptoFrames(connection_.transport_version())) {
     frame = QuicFrame(&crypto_frame_);
     EXPECT_CALL(visitor_, OnCryptoFrame(_)).Times(AnyNumber());
   } else {
     frame = QuicFrame(QuicStreamFrame(
         QuicUtils::GetCryptoStreamId(connection_.transport_version()), false,
         0u, QuicStringPiece()));
     EXPECT_CALL(visitor_, OnStreamFrame(_)).Times(AnyNumber());
   }
   ProcessFramePacketWithAddresses(frame, kSelfAddress, kPeerAddress);
   QuicAlarm* ack_alarm = QuicConnectionPeer::GetAckAlarm(&connection_);
   EXPECT_TRUE(ack_alarm->IsSet());
   ProcessFramePacketWithAddresses(QuicFrame(connection_close_frame.get()),
                                   kSelfAddress, kPeerAddress);
   // Verify ack alarm is not set.
   EXPECT_FALSE(ack_alarm->IsSet());
 }

 // Verify that a packet containing three coalesced packets is parsed correctly.
 TEST_P(QuicConnectionTest, CoalescedPacket) {
   if (!QuicVersionHasLongHeaderLengths(connection_.transport_version())) {
     // Coalesced packets can only be encoded using long header lengths.
     return;
   }
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
   EXPECT_TRUE(connection_.connected());
   if (QuicVersionUsesCryptoFrames(connection_.transport_version())) {
     EXPECT_CALL(visitor_, OnCryptoFrame(_)).Times(3);
   } else {
     EXPECT_CALL(visitor_, OnStreamFrame(_)).Times(3);
   }

   uint64_t packet_numbers[3] = {1, 2, 3};
   EncryptionLevel encryption_levels[3] = {
       ENCRYPTION_INITIAL, ENCRYPTION_INITIAL, ENCRYPTION_FORWARD_SECURE};
   char buffer[kMaxOutgoingPacketSize] = {};
   size_t total_encrypted_length = 0;
   for (int i = 0; i < 3; i++) {
     QuicPacketHeader header =
         ConstructPacketHeader(packet_numbers[i], encryption_levels[i]);
     QuicFrames frames;
     if (QuicVersionUsesCryptoFrames(connection_.transport_version())) {
       frames.push_back(QuicFrame(&crypto_frame_));
     } else {
       frames.push_back(QuicFrame(frame1_));
     }
     std::unique_ptr<QuicPacket> packet = ConstructPacket(header, frames);
     peer_creator_.set_encryption_level(encryption_levels[i]);
     size_t encrypted_length = peer_framer_.EncryptPayload(
         encryption_levels[i], QuicPacketNumber(packet_numbers[i]), *packet,
         buffer + total_encrypted_length,
         sizeof(buffer) - total_encrypted_length);
     EXPECT_GT(encrypted_length, 0u);
     total_encrypted_length += encrypted_length;
   }
   connection_.ProcessUdpPacket(
       kSelfAddress, kPeerAddress,
       QuicReceivedPacket(buffer, total_encrypted_length, clock_.Now(), false));
   if (connection_.GetSendAlarm()->IsSet()) {
     connection_.GetSendAlarm()->Fire();
   }

   EXPECT_TRUE(connection_.connected());
 }

 // Regression test for crbug.com/992831.
 TEST_P(QuicConnectionTest, CoalescedPacketThatSavesFrames) {
   if (!QuicVersionHasLongHeaderLengths(connection_.transport_version())) {
     // Coalesced packets can only be encoded using long header lengths.
     return;
   }
   if (connection_.SupportsMultiplePacketNumberSpaces()) {
     // TODO(b/129151114) Enable this test with multiple packet number spaces.
     return;
   }
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
   EXPECT_TRUE(connection_.connected());
   if (QuicVersionUsesCryptoFrames(connection_.transport_version())) {
     EXPECT_CALL(visitor_, OnCryptoFrame(_))
         .Times(3)
         .WillRepeatedly([this](const QuicCryptoFrame& /*frame*/) {
           // QuicFrame takes ownership of the QuicBlockedFrame.
           connection_.SendControlFrame(QuicFrame(new QuicBlockedFrame(1, 3)));
         });
   } else {
     EXPECT_CALL(visitor_, OnStreamFrame(_))
         .Times(3)
         .WillRepeatedly([this](const QuicStreamFrame& /*frame*/) {
           // QuicFrame takes ownership of the QuicBlockedFrame.
           connection_.SendControlFrame(QuicFrame(new QuicBlockedFrame(1, 3)));
         });
   }

   uint64_t packet_numbers[3] = {1, 2, 3};
   EncryptionLevel encryption_levels[3] = {
       ENCRYPTION_INITIAL, ENCRYPTION_INITIAL, ENCRYPTION_FORWARD_SECURE};
   char buffer[kMaxOutgoingPacketSize] = {};
   size_t total_encrypted_length = 0;
   for (int i = 0; i < 3; i++) {
     QuicPacketHeader header =
         ConstructPacketHeader(packet_numbers[i], encryption_levels[i]);
     QuicFrames frames;
     if (QuicVersionUsesCryptoFrames(connection_.transport_version())) {
       frames.push_back(QuicFrame(&crypto_frame_));
     } else {
       frames.push_back(QuicFrame(frame1_));
     }
     std::unique_ptr<QuicPacket> packet = ConstructPacket(header, frames);
     peer_creator_.set_encryption_level(encryption_levels[i]);
     size_t encrypted_length = peer_framer_.EncryptPayload(
         encryption_levels[i], QuicPacketNumber(packet_numbers[i]), *packet,
         buffer + total_encrypted_length,
         sizeof(buffer) - total_encrypted_length);
     EXPECT_GT(encrypted_length, 0u);
     total_encrypted_length += encrypted_length;
   }
   connection_.ProcessUdpPacket(
       kSelfAddress, kPeerAddress,
       QuicReceivedPacket(buffer, total_encrypted_length, clock_.Now(), false));
   if (connection_.GetSendAlarm()->IsSet()) {
     connection_.GetSendAlarm()->Fire();
   }

   EXPECT_TRUE(connection_.connected());

   SendAckPacketToPeer();
 }

 // Regresstion test for b/138962304.
 TEST_P(QuicConnectionTest, RtoAndWriteBlocked) {
   if (!connection_.session_decides_what_to_write()) {
     return;
   }
   EXPECT_FALSE(connection_.GetRetransmissionAlarm()->IsSet());

   QuicStreamId stream_id = 2;
   QuicPacketNumber last_data_packet;
   SendStreamDataToPeer(stream_id, "foo", 0, NO_FIN, &last_data_packet);
   EXPECT_TRUE(connection_.GetRetransmissionAlarm()->IsSet());

   // Writer gets blocked.
   writer_->SetWriteBlocked();

   // Cancel the stream.
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(0);
   EXPECT_CALL(visitor_, OnWriteBlocked()).Times(AtLeast(1));
   EXPECT_CALL(visitor_, WillingAndAbleToWrite())
       .WillRepeatedly(
           Invoke(&notifier_, &SimpleSessionNotifier::WillingToWrite));
   SendRstStream(stream_id, QUIC_ERROR_PROCESSING_STREAM, 3);

   // Retransmission timer fires in RTO mode.
   connection_.GetRetransmissionAlarm()->Fire();
   // Verify no packets get flushed when writer is blocked.
   EXPECT_EQ(0u, connection_.NumQueuedPackets());
 }

 // Regresstion test for b/138962304.
 TEST_P(QuicConnectionTest, TlpAndWriteBlocked) {
   if (!connection_.session_decides_what_to_write()) {
     return;
   }
   EXPECT_FALSE(connection_.GetRetransmissionAlarm()->IsSet());
   connection_.SetMaxTailLossProbes(1);

   QuicStreamId stream_id = 2;
   QuicPacketNumber last_data_packet;
   SendStreamDataToPeer(stream_id, "foo", 0, NO_FIN, &last_data_packet);
   SendStreamDataToPeer(4, "foo", 0, NO_FIN, &last_data_packet);
   EXPECT_TRUE(connection_.GetRetransmissionAlarm()->IsSet());

   // Writer gets blocked.
   writer_->SetWriteBlocked();

   // Cancel stream 2.
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(0);
   EXPECT_CALL(visitor_, OnWriteBlocked()).Times(AtLeast(1));
   SendRstStream(stream_id, QUIC_ERROR_PROCESSING_STREAM, 3);

   if (GetQuicReloadableFlag(quic_treat_queued_packets_as_sent)) {
     EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(1);
   } else {
     EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(0);
   }
   // Retransmission timer fires in TLP mode.
   connection_.GetRetransmissionAlarm()->Fire();
   // Verify one packets is forced flushed when writer is blocked.
   EXPECT_EQ(1u, connection_.NumQueuedPackets());
 }

 // Regresstion test for b/139375344.
 TEST_P(QuicConnectionTest, RtoForcesSendingPing) {
   if (!connection_.session_decides_what_to_write() ||
       connection_.PtoEnabled()) {
     return;
   }
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
   connection_.SetMaxTailLossProbes(2);
   EXPECT_EQ(0u, connection_.GetStats().tlp_count);
   EXPECT_EQ(0u, connection_.GetStats().rto_count);

   SendStreamDataToPeer(2, "foo", 0, NO_FIN, nullptr);
   QuicTime retransmission_time =
       connection_.GetRetransmissionAlarm()->deadline();
   EXPECT_NE(QuicTime::Zero(), retransmission_time);
   // TLP fires.
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, QuicPacketNumber(2), _, _));
   clock_.AdvanceTime(retransmission_time - clock_.Now());
   connection_.GetRetransmissionAlarm()->Fire();
   EXPECT_EQ(1u, connection_.GetStats().tlp_count);
   EXPECT_EQ(0u, connection_.GetStats().rto_count);
   EXPECT_TRUE(connection_.GetRetransmissionAlarm()->IsSet());

   // Packet 1 gets acked.
   QuicAckFrame frame = InitAckFrame(1);
   EXPECT_CALL(*send_algorithm_, OnCongestionEvent(_, _, _, _, _));
   ProcessAckPacket(1, &frame);
   EXPECT_TRUE(connection_.GetRetransmissionAlarm()->IsSet());
   retransmission_time = connection_.GetRetransmissionAlarm()->deadline();

   // RTO fires, verify a PING packet gets sent because there is no data to send.
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, QuicPacketNumber(3), _, _));
   EXPECT_CALL(visitor_, SendPing()).WillOnce(Invoke([this]() { SendPing(); }));
   clock_.AdvanceTime(retransmission_time - clock_.Now());
   connection_.GetRetransmissionAlarm()->Fire();
   EXPECT_EQ(1u, connection_.GetStats().tlp_count);
   EXPECT_EQ(1u, connection_.GetStats().rto_count);
   EXPECT_EQ(1u, writer_->ping_frames().size());
 }

 TEST_P(QuicConnectionTest, ProbeTimeout) {
   if (!connection_.session_decides_what_to_write()) {
     return;
   }
   SetQuicReloadableFlag(quic_enable_pto, true);
   QuicConfig config;
   QuicTagVector connection_options;
   connection_options.push_back(k2PTO);
   config.SetConnectionOptionsToSend(connection_options);
   EXPECT_CALL(*send_algorithm_, SetFromConfig(_, _));
   connection_.SetFromConfig(config);
   EXPECT_FALSE(connection_.GetRetransmissionAlarm()->IsSet());

   QuicStreamId stream_id = 2;
   QuicPacketNumber last_packet;
   SendStreamDataToPeer(stream_id, "foooooo", 0, NO_FIN, &last_packet);
   SendStreamDataToPeer(stream_id, "foooooo", 7, NO_FIN, &last_packet);
   EXPECT_TRUE(connection_.GetRetransmissionAlarm()->IsSet());

   // Reset stream.
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(1);
   SendRstStream(stream_id, QUIC_ERROR_PROCESSING_STREAM, 3);

   // Fire the PTO and verify only the RST_STREAM is resent, not stream data.
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(1);
   connection_.GetRetransmissionAlarm()->Fire();
   EXPECT_EQ(0u, writer_->stream_frames().size());
   EXPECT_EQ(1u, writer_->rst_stream_frames().size());
   EXPECT_TRUE(connection_.GetRetransmissionAlarm()->IsSet());
 }

 TEST_P(QuicConnectionTest, CloseConnectionAfter6ClientPTOs) {
   if (!connection_.session_decides_what_to_write()) {
     return;
   }
   SetQuicReloadableFlag(quic_enable_pto, true);
   QuicConfig config;
   QuicTagVector connection_options;
   connection_options.push_back(k1PTO);
   connection_options.push_back(k6PTO);
   config.SetConnectionOptionsToSend(connection_options);
   EXPECT_CALL(*send_algorithm_, SetFromConfig(_, _));
   connection_.SetFromConfig(config);
   EXPECT_FALSE(connection_.GetRetransmissionAlarm()->IsSet());

   // Send stream data.
   SendStreamDataToPeer(
       GetNthClientInitiatedStreamId(1, connection_.transport_version()), "foo",
       0, FIN, nullptr);

   // 5PTO + 1 connection close.
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(AtLeast(6));

   // Fire the retransmission alarm 5 times.
   for (int i = 0; i < 5; ++i) {
     connection_.GetRetransmissionAlarm()->Fire();
     EXPECT_TRUE(connection_.GetTimeoutAlarm()->IsSet());
     EXPECT_TRUE(connection_.connected());
   }

   EXPECT_EQ(0u, connection_.sent_packet_manager().GetConsecutiveTlpCount());
   EXPECT_EQ(0u, connection_.sent_packet_manager().GetConsecutiveRtoCount());
   EXPECT_EQ(5u, connection_.sent_packet_manager().GetConsecutivePtoCount());
   // Closes connection on 6th PTO.
   EXPECT_CALL(visitor_,
               OnConnectionClosed(_, ConnectionCloseSource::FROM_SELF));
   connection_.GetRetransmissionAlarm()->Fire();
   EXPECT_FALSE(connection_.GetTimeoutAlarm()->IsSet());
   EXPECT_FALSE(connection_.connected());
   TestConnectionCloseQuicErrorCode(QUIC_TOO_MANY_RTOS);
 }

 TEST_P(QuicConnectionTest, CloseConnectionAfter7ClientPTOs) {
   if (!connection_.session_decides_what_to_write()) {
     return;
   }
   SetQuicReloadableFlag(quic_enable_pto, true);
   QuicConfig config;
   QuicTagVector connection_options;
   connection_options.push_back(k2PTO);
   connection_options.push_back(k7PTO);
   config.SetConnectionOptionsToSend(connection_options);
   EXPECT_CALL(*send_algorithm_, SetFromConfig(_, _));
   connection_.SetFromConfig(config);
   EXPECT_FALSE(connection_.GetRetransmissionAlarm()->IsSet());

   // Send stream data.
   SendStreamDataToPeer(
       GetNthClientInitiatedStreamId(1, connection_.transport_version()), "foo",
       0, FIN, nullptr);

   // Fire the retransmission alarm 6 times.
   for (int i = 0; i < 6; ++i) {
     EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _));
     connection_.GetRetransmissionAlarm()->Fire();
     EXPECT_TRUE(connection_.GetTimeoutAlarm()->IsSet());
     EXPECT_TRUE(connection_.connected());
   }

   EXPECT_EQ(0u, connection_.sent_packet_manager().GetConsecutiveTlpCount());
   EXPECT_EQ(0u, connection_.sent_packet_manager().GetConsecutiveRtoCount());
   EXPECT_EQ(6u, connection_.sent_packet_manager().GetConsecutivePtoCount());
   // Closes connection on 7th PTO.
   EXPECT_CALL(visitor_,
               OnConnectionClosed(_, ConnectionCloseSource::FROM_SELF));
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(AtLeast(1));
   connection_.GetRetransmissionAlarm()->Fire();
   EXPECT_FALSE(connection_.GetTimeoutAlarm()->IsSet());
   EXPECT_FALSE(connection_.connected());
   TestConnectionCloseQuicErrorCode(QUIC_TOO_MANY_RTOS);
 }

 TEST_P(QuicConnectionTest, CloseConnectionAfter8ClientPTOs) {
   if (!connection_.session_decides_what_to_write()) {
     return;
   }
   SetQuicReloadableFlag(quic_enable_pto, true);
   QuicConfig config;
   QuicTagVector connection_options;
   connection_options.push_back(k2PTO);
   connection_options.push_back(k8PTO);
   config.SetConnectionOptionsToSend(connection_options);
   EXPECT_CALL(*send_algorithm_, SetFromConfig(_, _));
   connection_.SetFromConfig(config);
   EXPECT_FALSE(connection_.GetRetransmissionAlarm()->IsSet());

   // Send stream data.
   SendStreamDataToPeer(
       GetNthClientInitiatedStreamId(1, connection_.transport_version()), "foo",
       0, FIN, nullptr);

   // Fire the retransmission alarm 7 times.
   for (int i = 0; i < 7; ++i) {
     EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _));
     connection_.GetRetransmissionAlarm()->Fire();
     EXPECT_TRUE(connection_.GetTimeoutAlarm()->IsSet());
     EXPECT_TRUE(connection_.connected());
   }

   EXPECT_EQ(0u, connection_.sent_packet_manager().GetConsecutiveTlpCount());
   EXPECT_EQ(0u, connection_.sent_packet_manager().GetConsecutiveRtoCount());
   EXPECT_EQ(7u, connection_.sent_packet_manager().GetConsecutivePtoCount());
   // Closes connection on 8th PTO.
   EXPECT_CALL(visitor_,
               OnConnectionClosed(_, ConnectionCloseSource::FROM_SELF));
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(AtLeast(1));
   connection_.GetRetransmissionAlarm()->Fire();
   EXPECT_FALSE(connection_.GetTimeoutAlarm()->IsSet());
   EXPECT_FALSE(connection_.connected());
   TestConnectionCloseQuicErrorCode(QUIC_TOO_MANY_RTOS);
 }

 TEST_P(QuicConnectionTest, DeprecateHandshakeMode) {
   if (!connection_.version().SupportsAntiAmplificationLimit()) {
     return;
   }
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
   EXPECT_FALSE(connection_.GetRetransmissionAlarm()->IsSet());

   // Send CHLO.
   connection_.SendCryptoStreamData();
   EXPECT_TRUE(connection_.GetRetransmissionAlarm()->IsSet());

   EXPECT_CALL(*loss_algorithm_, DetectLosses(_, _, _, _, _, _));
   EXPECT_CALL(*send_algorithm_, OnCongestionEvent(true, _, _, _, _));
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(0);
   QuicAckFrame frame1 = InitAckFrame(1);
   // Received ACK for packet 1.
   ProcessFramePacketAtLevel(1, QuicFrame(&frame1), ENCRYPTION_INITIAL);

   // Verify retransmission alarm is still set because handshake is not
   // confirmed although there is nothing in flight.
   EXPECT_TRUE(connection_.GetRetransmissionAlarm()->IsSet());
   EXPECT_EQ(0u, connection_.GetStats().pto_count);
   EXPECT_EQ(0u, connection_.GetStats().crypto_retransmit_count);

   // PTO fires, verify a PING packet gets sent because there is no data to send.
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, QuicPacketNumber(2), _, _));
   EXPECT_CALL(visitor_, SendPing()).WillOnce(Invoke([this]() { SendPing(); }));
   connection_.GetRetransmissionAlarm()->Fire();
   EXPECT_EQ(1u, connection_.GetStats().pto_count);
   EXPECT_EQ(0u, connection_.GetStats().crypto_retransmit_count);
   EXPECT_EQ(1u, writer_->ping_frames().size());
 }

 TEST_P(QuicConnectionTest, AntiAmplificationLimit) {
   if (!connection_.version().SupportsAntiAmplificationLimit()) {
     return;
   }
   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
   EXPECT_CALL(visitor_, OnCryptoFrame(_)).Times(AnyNumber());

   set_perspective(Perspective::IS_SERVER);
   // Verify no data can be sent at the beginning because bytes received is 0.
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(0);
   connection_.SendCryptoDataWithString("foo", 0);
   EXPECT_FALSE(connection_.GetRetransmissionAlarm()->IsSet());

   // Receives packet 1.
   ProcessCryptoPacketAtLevel(1, ENCRYPTION_INITIAL);

   const size_t anti_amplification_factor =
       GetQuicFlag(FLAGS_quic_anti_amplification_factor);
   // Verify now packets can be sent.
   for (size_t i = 0; i < anti_amplification_factor; ++i) {
     EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(1);
     connection_.SendCryptoDataWithString("foo", i * 3);
     // Verify retransmission alarm is not set if throttled by anti-amplification
     // limit.
     EXPECT_EQ(i != anti_amplification_factor - 1,
               connection_.GetRetransmissionAlarm()->IsSet());
   }
   // Verify server is throttled by anti-amplification limit.
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(0);
   connection_.SendCryptoDataWithString("foo", anti_amplification_factor * 3);

   // Receives packet 2.
   ProcessCryptoPacketAtLevel(2, ENCRYPTION_INITIAL);
   // Verify more packets can be sent.
   for (size_t i = anti_amplification_factor; i < anti_amplification_factor * 2;
        ++i) {
     EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(1);
     connection_.SendCryptoDataWithString("foo", i * 3);
   }
   // Verify server is throttled by anti-amplification limit.
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(0);
   connection_.SendCryptoDataWithString("foo",
                                        2 * anti_amplification_factor * 3);

   ProcessPacket(3);
   // Verify anti-amplification limit is gone after address validation.
   for (size_t i = 0; i < 100; ++i) {
     EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(1);
     connection_.SendStreamDataWithString(3, "first", i * 0, NO_FIN);
   }
 }

 TEST_P(QuicConnectionTest, ConnectionCloseFrameType) {
   if (!VersionHasIetfQuicFrames(version().transport_version)) {
     // Test relevent only for IETF QUIC.
     return;
   }
   const QuicErrorCode kQuicErrorCode = IETF_QUIC_PROTOCOL_VIOLATION;
   // Use the (unknown) frame type of 9999 to avoid triggering any logic
   // which might be associated with the processing of a known frame type.
   const uint64_t kTransportCloseFrameType = 9999u;
   QuicFramerPeer::set_current_received_frame_type(
       QuicConnectionPeer::GetFramer(&connection_), kTransportCloseFrameType);
   // Do a transport connection close
   EXPECT_CALL(visitor_, OnConnectionClosed(_, _));
   connection_.CloseConnection(
       kQuicErrorCode, "Some random error message",
       ConnectionCloseBehavior::SEND_CONNECTION_CLOSE_PACKET);
   const std::vector<QuicConnectionCloseFrame>& connection_close_frames =
       writer_->connection_close_frames();
   ASSERT_EQ(1u, connection_close_frames.size());
   EXPECT_EQ(IETF_QUIC_TRANSPORT_CONNECTION_CLOSE,
             connection_close_frames[0].close_type);
   EXPECT_EQ(kQuicErrorCode, connection_close_frames[0].extracted_error_code);
   EXPECT_EQ(kTransportCloseFrameType,
             connection_close_frames[0].transport_close_frame_type);
 }

 // Regression test for b/137401387 and b/138962304.
 TEST_P(QuicConnectionTest, RtoPacketAsTwo) {
   if (!connection_.session_decides_what_to_write() ||
       connection_.PtoEnabled()) {
     return;
   }
   connection_.SetMaxTailLossProbes(1);
   connection_.SetDefaultEncryptionLevel(ENCRYPTION_FORWARD_SECURE);
   std::string stream_data(3000, 's');
   // Send packets 1 - 66 and exhaust cwnd.
   for (size_t i = 0; i < 22; ++i) {
     // 3 packets for each stream, the first 2 are guaranteed to be full packets.
     SendStreamDataToPeer(i + 2, stream_data, 0, FIN, nullptr);
   }
   CongestionBlockWrites();

   // Fires TLP. Please note, this tail loss probe has 1 byte less stream data
   // compared to packet 1 because packet number length increases.
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, QuicPacketNumber(67), _, _));
   connection_.GetRetransmissionAlarm()->Fire();
   // Fires RTO. Please note, although packets 2 and 3 *should* be RTOed, but
   // packet 2 gets RTOed to two packets because packet number length increases.
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, QuicPacketNumber(68), _, _));
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, QuicPacketNumber(69), _, _));
   connection_.GetRetransmissionAlarm()->Fire();

   EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
   // Resets all streams except 2 and ack packets 1 and 2. Now, packet 3 is the
   // only one containing retransmittable frames.
   for (size_t i = 1; i < 22; ++i) {
     notifier_.OnStreamReset(i + 2, QUIC_STREAM_CANCELLED);
   }
   EXPECT_CALL(*send_algorithm_, OnCongestionEvent(_, _, _, _, _));
   QuicAckFrame frame =
       InitAckFrame({{QuicPacketNumber(1), QuicPacketNumber(3)}});
   ProcessAckPacket(1, &frame);
   CongestionUnblockWrites();

   // Fires TLP, verify a PING gets sent because packet 3 is marked
   // RTO_RETRANSMITTED.
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, QuicPacketNumber(70), _, _));
   EXPECT_CALL(visitor_, SendPing()).WillOnce(Invoke([this]() { SendPing(); }));
   connection_.GetRetransmissionAlarm()->Fire();
 }

 TEST_P(QuicConnectionTest, PtoSkipsPacketNumber) {
   if (!connection_.session_decides_what_to_write()) {
     return;
   }
   SetQuicReloadableFlag(quic_enable_pto, true);
   SetQuicReloadableFlag(quic_skip_packet_number_for_pto, true);
   QuicConfig config;
   QuicTagVector connection_options;
   connection_options.push_back(k1PTO);
   connection_options.push_back(kPTOS);
   config.SetConnectionOptionsToSend(connection_options);
   EXPECT_CALL(*send_algorithm_, SetFromConfig(_, _));
   connection_.SetFromConfig(config);
   EXPECT_FALSE(connection_.GetRetransmissionAlarm()->IsSet());

   QuicStreamId stream_id = 2;
   QuicPacketNumber last_packet;
   SendStreamDataToPeer(stream_id, "foooooo", 0, NO_FIN, &last_packet);
   SendStreamDataToPeer(stream_id, "foooooo", 7, NO_FIN, &last_packet);
   EXPECT_EQ(QuicPacketNumber(2), last_packet);
   EXPECT_TRUE(connection_.GetRetransmissionAlarm()->IsSet());

   // Fire PTO and verify the PTO retransmission skips one packet number.
   EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(1);
   connection_.GetRetransmissionAlarm()->Fire();
   EXPECT_EQ(1u, writer_->stream_frames().size());
   EXPECT_EQ(QuicPacketNumber(4), writer_->last_packet_header().packet_number);
   EXPECT_TRUE(connection_.GetRetransmissionAlarm()->IsSet());
 }

 }  // namespace
 }  // namespace test
 }  // namespace quic