diff --git a/quic/quartc/test/quartc_peer.h b/quic/quartc/test/quartc_peer.h
new file mode 100644
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+++ b/quic/quartc/test/quartc_peer.h
@@ -0,0 +1,105 @@
+// Copyright (c) 2019 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.
+
+#ifndef QUICHE_QUIC_QUARTC_TEST_QUARTC_PEER_H_
+#define QUICHE_QUIC_QUARTC_TEST_QUARTC_PEER_H_
+
+#include <string>
+
+#include "net/third_party/quiche/src/quic/core/crypto/quic_random.h"
+#include "net/third_party/quiche/src/quic/core/quic_alarm_factory.h"
+#include "net/third_party/quiche/src/quic/core/quic_bandwidth.h"
+#include "net/third_party/quiche/src/quic/core/quic_error_codes.h"
+#include "net/third_party/quiche/src/quic/core/quic_time.h"
+#include "net/third_party/quiche/src/quic/core/quic_types.h"
+#include "net/third_party/quiche/src/quic/platform/api/quic_containers.h"
+#include "net/third_party/quiche/src/quic/platform/api/quic_string_piece.h"
+#include "net/third_party/quiche/src/quic/quartc/quartc_endpoint.h"
+#include "net/third_party/quiche/src/quic/quartc/quartc_session.h"
+#include "net/third_party/quiche/src/quic/quartc/quartc_stream.h"
+#include "net/third_party/quiche/src/quic/quartc/test/quartc_data_source.h"
+
+namespace quic {
+namespace test {
+
+// ParsedQuartcDataFrame with a receive_time.
+struct ReceivedMessage {
+  ParsedQuartcDataFrame frame;
+  QuicTime receive_time = QuicTime::Zero();
+};
+
+// Test utility that adapts QuartcDataSources to a QuartcSession.
+// The utility creates and manages a set of QuartcDataSources.  It sends the
+// data produced by those sources as QUIC datagram frames.  It reconfigures the
+// maximum frame size of each source in order to fit test frames into QUIC
+// datagram frames.  It also adjusts the bitrate of each source to fit within
+// the bandwidth available to the session.
+class QuartcPeer : public QuartcEndpoint::Delegate,
+                   public QuartcSession::Delegate,
+                   public QuartcDataSource::Delegate {
+ public:
+  // Creates a QuartcPeer that sends data from a set of sources described by
+  // |configs|.  Note that the max frame size of each config may be adjusted in
+  // order to fit within the constraints of the QUIC session.
+  QuartcPeer(const QuicClock* clock,
+             QuicAlarmFactory* alarm_factory,
+             QuicRandom* random,
+             const std::vector<QuartcDataSource::Config>& configs);
+  QuartcPeer(QuartcPeer&) = delete;
+  QuartcPeer& operator=(QuartcPeer&) = delete;
+
+  ~QuartcPeer();
+
+  // Messages received from the peer, in the order they were received.
+  const std::vector<ReceivedMessage>& received_messages() const {
+    return received_messages_;
+  }
+
+  // QuartcEndpoint::Delegate overrides.
+  void OnSessionCreated(QuartcSession* session) override;
+  void OnConnectError(QuicErrorCode error,
+                      const std::string& error_details) override;
+
+  // QuartcSession::Delegate overrides.
+  void OnCryptoHandshakeComplete() override;
+  void OnConnectionWritable() override;
+  void OnIncomingStream(QuartcStream* stream) override;
+  void OnCongestionControlChange(QuicBandwidth bandwidth_estimate,
+                                 QuicBandwidth pacing_rate,
+                                 QuicTime::Delta latest_rtt) override;
+  void OnConnectionClosed(QuicErrorCode error_code,
+                          const std::string& error_details,
+                          ConnectionCloseSource source) override;
+  void OnMessageReceived(QuicStringPiece message) override;
+
+  // QuartcDataSource::Delegate overrides.
+  void OnDataProduced(const char* data, size_t length) override;
+
+ private:
+  const QuicClock* clock_;
+  QuicAlarmFactory* alarm_factory_;
+  QuicRandom* random_;
+
+  // Session used for sending and receiving data.  Not owned.  Created by an
+  // external QuartcEndpoint and set in the |OnSessionCreated| callback.
+  QuartcSession* session_;
+
+  // Saved copy of the configs for data sources.  These configs may be modified
+  // before |data_sources_| are initialized (for example, to set appropriate
+  // max frame sizes).
+  std::vector<QuartcDataSource::Config> configs_;
+
+  // Data sources are initialized once the session is created and enabled once
+  // the session is able to send.
+  std::vector<std::unique_ptr<QuartcDataSource>> data_sources_;
+
+  // Messages received by this peer from the remote peer.  Stored in the order
+  // they are received.
+  std::vector<ReceivedMessage> received_messages_;
+};
+
+}  // namespace test
+}  // namespace quic
+
+#endif  // QUICHE_QUIC_QUARTC_FAKE_QUARTC_PEER_H_