Refactor QpackEncoderTest.

Add QpackEncoder member used across Encode() calls instead of initiating a local
one each time.  Use mock delegate instead of noop delegate for encoder stream
sender, currently no change since the encoder does not use the dynamic table yet
therefore it does not send anything on the encoder stream.

gfe-relnote: n/a, test-only change.
PiperOrigin-RevId: 263344396
Change-Id: Ib5fcd6364ea998f6f5edc1f9a66fc886101c4511
diff --git a/quic/core/qpack/qpack_encoder_test.cc b/quic/core/qpack/qpack_encoder_test.cc
index 8de95e4..bf5116e 100644
--- a/quic/core/qpack/qpack_encoder_test.cc
+++ b/quic/core/qpack/qpack_encoder_test.cc
@@ -7,6 +7,7 @@
 #include <string>
 
 #include "net/third_party/quiche/src/quic/core/qpack/qpack_encoder_test_utils.h"
+#include "net/third_party/quiche/src/quic/core/qpack/qpack_test_utils.h"
 #include "net/third_party/quiche/src/quic/core/qpack/qpack_utils.h"
 #include "net/third_party/quiche/src/quic/platform/api/quic_test.h"
 #include "net/third_party/quiche/src/quic/platform/api/quic_text_utils.h"
@@ -21,17 +22,20 @@
 
 class QpackEncoderTest : public QuicTest {
  protected:
-  QpackEncoderTest() = default;
+  QpackEncoderTest() : encoder_(&decoder_stream_error_delegate_) {
+    encoder_.set_qpack_stream_sender_delegate(&encoder_stream_sender_delegate_);
+    encoder_.SetMaximumBlockedStreams(1);
+  }
+
   ~QpackEncoderTest() override = default;
 
   std::string Encode(const spdy::SpdyHeaderBlock* header_list) {
-    QpackEncoder encoder(&decoder_stream_error_delegate_);
-    encoder.set_qpack_stream_sender_delegate(&encoder_stream_sender_delegate_);
-    return encoder.EncodeHeaderList(/* stream_id = */ 1, header_list);
+    return encoder_.EncodeHeaderList(/* stream_id = */ 1, header_list);
   }
 
   StrictMock<MockDecoderStreamErrorDelegate> decoder_stream_error_delegate_;
-  NoopQpackStreamSenderDelegate encoder_stream_sender_delegate_;
+  StrictMock<MockQpackStreamSenderDelegate> encoder_stream_sender_delegate_;
+  QpackEncoder encoder_;
 };
 
 TEST_F(QpackEncoderTest, Empty) {