Injectable audio encoders: WebRtcVoiceEngine and company

webrtc/audio/audio_send_stream_unittest.cc

 /*
  *  Copyright (c) 2015 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
 #include <string>
+#include <utility>
 #include <vector>
 
 #include "webrtc/audio/audio_send_stream.h"
 #include "webrtc/audio/audio_state.h"
 #include "webrtc/audio/conversion.h"
 #include "webrtc/base/task_queue.h"
 #include "webrtc/logging/rtc_event_log/mock/mock_rtc_event_log.h"
+#include "webrtc/modules/audio_coding/codecs/mock/mock_audio_encoder.h"
+#include "webrtc/modules/audio_coding/codecs/mock/mock_audio_encoder_factory.h"
 #include "webrtc/modules/audio_mixer/audio_mixer_impl.h"
 #include "webrtc/modules/audio_processing/include/mock_audio_processing.h"
 #include "webrtc/modules/congestion_controller/include/congestion_controller.h"
 #include "webrtc/modules/congestion_controller/include/mock/mock_congestion_controller.h"
 #include "webrtc/modules/pacing/paced_sender.h"
 #include "webrtc/modules/rtp_rtcp/mocks/mock_rtcp_rtt_stats.h"
 #include "webrtc/test/gtest.h"
 #include "webrtc/test/mock_voe_channel_proxy.h"
 #include "webrtc/test/mock_voice_engine.h"
 #include "webrtc/voice_engine/transmit_mixer.h"
 
 namespace webrtc {
 namespace test {
 namespace {
 
 using testing::_;
 using testing::Eq;
 using testing::Ne;
+using testing::Invoke;
 using testing::Return;
 
 const int kChannelId = 1;
 const uint32_t kSsrc = 1234;
 const char* kCName = "foo_name";
 const int kAudioLevelId = 2;
 const int kTransportSequenceNumberId = 4;
 const int kEchoDelayMedian = 254;
 const int kEchoDelayStdDev = -3;
 const int kEchoReturnLoss = -65;
 const int kEchoReturnLossEnhancement = 101;
 const float kResidualEchoLikelihood = -1.0f;
 const int32_t kSpeechInputLevel = 96;
 const CallStatistics kCallStats = {
     1345,  1678,  1901, 1234,  112, 13456, 17890, 1567, -1890, -1123};
 const ReportBlock kReportBlock = {456, 780, 123, 567, 890, 132, 143, 13354};
 const int kTelephoneEventPayloadType = 123;
 const int kTelephoneEventPayloadFrequency = 65432;
 const int kTelephoneEventCode = 45;
 const int kTelephoneEventDuration = 6789;
 const CodecInst kIsacCodec = {103, "isac", 16000, 320, 1, 32000};
+constexpr int kIsacPayloadType = 103;
+const SdpAudioFormat kIsacFormat = {"isac", 16000, 1};
+const SdpAudioFormat kOpusFormat = {"opus", 48000, 2};
+const SdpAudioFormat kG722Format = {"g722", 8000, 1};
+const AudioCodecSpec kCodecSpecs[] = {
+    {kIsacFormat, {16000, 1, 32000, 10000, 32000}},
+    {kOpusFormat, {48000, 1, 32000, 6000, 510000}},
+    {kG722Format, {16000, 1, 64000}}};
 
 class MockLimitObserver : public BitrateAllocator::LimitObserver {
  public:
   MOCK_METHOD2(OnAllocationLimitsChanged,
                void(uint32_t min_send_bitrate_bps,
                     uint32_t max_padding_bitrate_bps));
 };
 
 class MockTransmitMixer : public voe::TransmitMixer {
  public:
   MOCK_CONST_METHOD0(AudioLevelFullRange, int16_t());
 };
 
+std::unique_ptr<MockAudioEncoder> SetupAudioEncoderMock(
+    int payload_type,
+    const SdpAudioFormat& format) {
+  for (const auto& spec : kCodecSpecs) {
+    if (format == spec.format) {
+      std::unique_ptr<MockAudioEncoder> encoder(new MockAudioEncoder);
+      ON_CALL(*encoder.get(), SampleRateHz())
+          .WillByDefault(Return(spec.info.sample_rate_hz));
+      ON_CALL(*encoder.get(), NumChannels())
+          .WillByDefault(Return(spec.info.num_channels));
+      ON_CALL(*encoder.get(), RtpTimestampRateHz())
+          .WillByDefault(Return(spec.format.clockrate_hz));
+      return encoder;
+    }
+  }
+  return nullptr;
+}
+
+rtc::scoped_refptr<MockAudioEncoderFactory> SetupEncoderFactoryMock() {
+  rtc::scoped_refptr<MockAudioEncoderFactory> factory =
+      new rtc::RefCountedObject<MockAudioEncoderFactory>();
+  ON_CALL(*factory.get(), GetSupportedEncoders())
+      .WillByDefault(Return(std::vector<AudioCodecSpec>(
+          std::begin(kCodecSpecs), std::end(kCodecSpecs))));
+  ON_CALL(*factory.get(), QueryAudioEncoder(_))
+      .WillByDefault(Invoke([](const SdpAudioFormat& format) {
+        for (const auto& spec : kCodecSpecs) {
+          if (format == spec.format) {
+            return rtc::Optional<AudioCodecInfo>(spec.info);
+          }
+        }
+        return rtc::Optional<AudioCodecInfo>();
+      }));
+  ON_CALL(*factory.get(), MakeAudioEncoderMock(_, _, _))
+      .WillByDefault(Invoke([](int payload_type, const SdpAudioFormat& format,
+                               std::unique_ptr<AudioEncoder>* return_value) {
+        *return_value = SetupAudioEncoderMock(payload_type, format);
+      }));
+  return factory;
+}
+
 struct ConfigHelper {
-  explicit ConfigHelper(bool audio_bwe_enabled)
+  ConfigHelper(bool audio_bwe_enabled, bool expect_set_encoder_call)
       : simulated_clock_(123456),
         stream_config_(nullptr),
         congestion_controller_(&simulated_clock_,
                                &bitrate_observer_,
                                nullptr,
                                &event_log_,
                                &packet_router_),
         bitrate_allocator_(&limit_observer_),
         worker_queue_("ConfigHelper_worker_queue") {
     using testing::Invoke;
@@ skipping 11 matching lines @@
     config.audio_mixer = AudioMixerImpl::Create();
     audio_state_ = AudioState::Create(config);
 
     SetupDefaultChannelProxy(audio_bwe_enabled);
 
     EXPECT_CALL(voice_engine_, ChannelProxyFactory(kChannelId))
         .WillOnce(Invoke([this](int channel_id) {
           return channel_proxy_;
         }));
 
-    SetupMockForSetupSendCodec();
+    SetupMockForSetupSendCodec(expect_set_encoder_call);
 
+    // Use ISAC as default codec so as to prevent unnecessary |voice_engine_|
+    // calls from the default ctor behavior.
+    stream_config_.send_codec_spec =
+        rtc::Optional<AudioSendStream::Config::SendCodecSpec>(
+            {kIsacPayloadType, kIsacFormat});
     stream_config_.voe_channel_id = kChannelId;
     stream_config_.rtp.ssrc = kSsrc;
     stream_config_.rtp.nack.rtp_history_ms = 200;
     stream_config_.rtp.c_name = kCName;
     stream_config_.rtp.extensions.push_back(
         RtpExtension(RtpExtension::kAudioLevelUri, kAudioLevelId));
     if (audio_bwe_enabled) {
       stream_config_.rtp.extensions.push_back(
           RtpExtension(RtpExtension::kTransportSequenceNumberUri,
                        kTransportSequenceNumberId));
-      stream_config_.send_codec_spec.transport_cc_enabled = true;
+      stream_config_.send_codec_spec->transport_cc_enabled = true;
     }
-    // Use ISAC as default codec so as to prevent unnecessary |voice_engine_|
-    // calls from the default ctor behavior.
-    stream_config_.send_codec_spec.codec_inst = kIsacCodec;
+    stream_config_.encoder_factory = SetupEncoderFactoryMock();
     stream_config_.min_bitrate_bps = 10000;
     stream_config_.max_bitrate_bps = 65000;
   }
 
   AudioSendStream::Config& config() { return stream_config_; }
+  MockAudioEncoderFactory& mock_encoder_factory() {
+    return *static_cast<MockAudioEncoderFactory*>(
+        stream_config_.encoder_factory.get());
+  }
   rtc::scoped_refptr<AudioState> audio_state() { return audio_state_; }
   MockVoEChannelProxy* channel_proxy() { return channel_proxy_; }
   PacketRouter* packet_router() { return &packet_router_; }
   CongestionController* congestion_controller() {
     return &congestion_controller_;
   }
   BitrateAllocator* bitrate_allocator() { return &bitrate_allocator_; }
   rtc::TaskQueue* worker_queue() { return &worker_queue_; }
   RtcEventLog* event_log() { return &event_log_; }
   MockVoiceEngine* voice_engine() { return &voice_engine_; }
@@ skipping 29 matching lines @@
     EXPECT_CALL(*channel_proxy_, RegisterExternalTransport(nullptr)).Times(1);
     EXPECT_CALL(*channel_proxy_, DeRegisterExternalTransport()).Times(1);
     EXPECT_CALL(*channel_proxy_, SetRtcEventLog(testing::NotNull())).Times(1);
     EXPECT_CALL(*channel_proxy_, SetRtcEventLog(testing::IsNull()))
         .Times(1);  // Destructor resets the event log
     EXPECT_CALL(*channel_proxy_, SetRtcpRttStats(&rtcp_rtt_stats_)).Times(1);
     EXPECT_CALL(*channel_proxy_, SetRtcpRttStats(testing::IsNull()))
         .Times(1);  // Destructor resets the rtt stats.
   }
 
-  void SetupMockForSetupSendCodec() {
-    EXPECT_CALL(*channel_proxy_, SetVADStatus(false))
-        .WillOnce(Return(true));
-    EXPECT_CALL(*channel_proxy_, SetCodecFECStatus(false))
-        .WillOnce(Return(true));
-    EXPECT_CALL(*channel_proxy_, DisableAudioNetworkAdaptor());
-    // Let |GetSendCodec| return false for the first time to indicate that no
-    // send codec has been set.
-    EXPECT_CALL(*channel_proxy_, GetSendCodec(_)).WillOnce(Return(false));
-    EXPECT_CALL(*channel_proxy_, SetSendCodec(_)).WillOnce(Return(true));
+  void SetupMockForSetupSendCodec(bool expect_set_encoder_call) {
+    if (expect_set_encoder_call) {
+      EXPECT_CALL(*channel_proxy_, SetEncoderForMock(_, _))
+          .WillOnce(Return(true));
+    }
   }
+
   RtcpRttStats* rtcp_rtt_stats() { return &rtcp_rtt_stats_; }
 
   void SetupMockForSendTelephoneEvent() {
     EXPECT_TRUE(channel_proxy_);
     EXPECT_CALL(*channel_proxy_,
         SetSendTelephoneEventPayloadType(kTelephoneEventPayloadType,
                                          kTelephoneEventPayloadFrequency))
             .WillOnce(Return(true));
     EXPECT_CALL(*channel_proxy_,
         SendTelephoneEventOutband(kTelephoneEventCode, kTelephoneEventDuration))
@@ skipping 11 matching lines @@
     block.source_SSRC = kSsrc;
     report_blocks.push_back(block);  // Correct block.
     block.fraction_lost = 0;
     report_blocks.push_back(block);  // Duplicate SSRC, bad fraction_lost.
 
     EXPECT_TRUE(channel_proxy_);
     EXPECT_CALL(*channel_proxy_, GetRTCPStatistics())
         .WillRepeatedly(Return(kCallStats));
     EXPECT_CALL(*channel_proxy_, GetRemoteRTCPReportBlocks())
         .WillRepeatedly(Return(report_blocks));
-    EXPECT_CALL(*channel_proxy_, GetSendCodec(_))
-        .WillRepeatedly(DoAll(SetArgPointee<0>(kIsacCodec), Return(true)));
     EXPECT_CALL(voice_engine_, transmit_mixer())
         .WillRepeatedly(Return(&transmit_mixer_));
     EXPECT_CALL(voice_engine_, audio_processing())
         .WillRepeatedly(Return(&audio_processing_));
 
     EXPECT_CALL(transmit_mixer_, AudioLevelFullRange())
         .WillRepeatedly(Return(kSpeechInputLevel));
 
     // We have to set the instantaneous value, the average, min and max. We only
     // care about the instantaneous value, so we set all to the same value.
@@ skipping 31 matching lines @@
 };
 }  // namespace
 
 TEST(AudioSendStreamTest, ConfigToString) {
   AudioSendStream::Config config(nullptr);
   config.rtp.ssrc = kSsrc;
   config.rtp.c_name = kCName;
   config.voe_channel_id = kChannelId;
   config.min_bitrate_bps = 12000;
   config.max_bitrate_bps = 34000;
-  config.send_codec_spec.nack_enabled = true;
-  config.send_codec_spec.transport_cc_enabled = false;
-  config.send_codec_spec.enable_codec_fec = true;
-  config.send_codec_spec.enable_opus_dtx = false;
-  config.send_codec_spec.opus_max_playback_rate = 32000;
-  config.send_codec_spec.cng_payload_type = 42;
-  config.send_codec_spec.cng_plfreq = 56;
-  config.send_codec_spec.min_ptime_ms = 20;
-  config.send_codec_spec.max_ptime_ms = 60;
-  config.send_codec_spec.codec_inst = kIsacCodec;
+  config.send_codec_spec =
+      rtc::Optional<AudioSendStream::Config::SendCodecSpec>(
+          {kIsacPayloadType, kIsacFormat});
+  config.send_codec_spec->nack_enabled = true;
+  config.send_codec_spec->transport_cc_enabled = false;
+  config.send_codec_spec->cng_payload_type = rtc::Optional<int>(42);
+  config.encoder_factory = MockAudioEncoderFactory::CreateUnusedFactory();
   config.rtp.extensions.push_back(
       RtpExtension(RtpExtension::kAudioLevelUri, kAudioLevelId));
   EXPECT_EQ(
       "{rtp: {ssrc: 1234, extensions: [{uri: "
       "urn:ietf:params:rtp-hdrext:ssrc-audio-level, id: 2}], nack: "
       "{rtp_history_ms: 0}, c_name: foo_name}, send_transport: null, "
       "voe_channel_id: 1, min_bitrate_bps: 12000, max_bitrate_bps: 34000, "
       "send_codec_spec: {nack_enabled: true, transport_cc_enabled: false, "
-      "enable_codec_fec: true, enable_opus_dtx: false, opus_max_playback_rate: "
-      "32000, cng_payload_type: 42, cng_plfreq: 56, min_ptime: 20, max_ptime: "
-      "60, codec_inst: {pltype: 103, plname: \"isac\", plfreq: 16000, pacsize: "
-      "320, channels: 1, rate: 32000}}}",
+      "cng_payload_type: 42, payload_type: 103, "
+      "format: {name: isac, clockrate_hz: 16000, num_channels: 1, "
+      "parameters: {}}}}",
       config.ToString());
 }
 
 TEST(AudioSendStreamTest, ConstructDestruct) {
-  ConfigHelper helper(false);
+  ConfigHelper helper(false, true);
   internal::AudioSendStream send_stream(
       helper.config(), helper.audio_state(), helper.worker_queue(),
       helper.packet_router(), helper.congestion_controller(),
       helper.bitrate_allocator(), helper.event_log(), helper.rtcp_rtt_stats());
 }
 
 TEST(AudioSendStreamTest, SendTelephoneEvent) {
-  ConfigHelper helper(false);
+  ConfigHelper helper(false, true);
   internal::AudioSendStream send_stream(
       helper.config(), helper.audio_state(), helper.worker_queue(),
       helper.packet_router(), helper.congestion_controller(),
       helper.bitrate_allocator(), helper.event_log(), helper.rtcp_rtt_stats());
   helper.SetupMockForSendTelephoneEvent();
   EXPECT_TRUE(send_stream.SendTelephoneEvent(kTelephoneEventPayloadType,
       kTelephoneEventPayloadFrequency, kTelephoneEventCode,
       kTelephoneEventDuration));
 }
 
 TEST(AudioSendStreamTest, SetMuted) {
-  ConfigHelper helper(false);
+  ConfigHelper helper(false, true);
   internal::AudioSendStream send_stream(
       helper.config(), helper.audio_state(), helper.worker_queue(),
       helper.packet_router(), helper.congestion_controller(),
       helper.bitrate_allocator(), helper.event_log(), helper.rtcp_rtt_stats());
   EXPECT_CALL(*helper.channel_proxy(), SetInputMute(true));
   send_stream.SetMuted(true);
 }
 
 TEST(AudioSendStreamTest, AudioBweCorrectObjectsOnChannelProxy) {
-  ConfigHelper helper(true);
+  ConfigHelper helper(true, true);
   internal::AudioSendStream send_stream(
       helper.config(), helper.audio_state(), helper.worker_queue(),
       helper.packet_router(), helper.congestion_controller(),
       helper.bitrate_allocator(), helper.event_log(), helper.rtcp_rtt_stats());
 }
 
 TEST(AudioSendStreamTest, NoAudioBweCorrectObjectsOnChannelProxy) {
-  ConfigHelper helper(false);
+  ConfigHelper helper(false, true);
   internal::AudioSendStream send_stream(
       helper.config(), helper.audio_state(), helper.worker_queue(),
       helper.packet_router(), helper.congestion_controller(),
       helper.bitrate_allocator(), helper.event_log(), helper.rtcp_rtt_stats());
 }
 
 TEST(AudioSendStreamTest, GetStats) {
-  ConfigHelper helper(false);
+  ConfigHelper helper(false, true);
   internal::AudioSendStream send_stream(
       helper.config(), helper.audio_state(), helper.worker_queue(),
       helper.packet_router(), helper.congestion_controller(),
       helper.bitrate_allocator(), helper.event_log(), helper.rtcp_rtt_stats());
   helper.SetupMockForGetStats();
   AudioSendStream::Stats stats = send_stream.GetStats();
   EXPECT_EQ(kSsrc, stats.local_ssrc);
   EXPECT_EQ(static_cast<int64_t>(kCallStats.bytesSent), stats.bytes_sent);
   EXPECT_EQ(kCallStats.packetsSent, stats.packets_sent);
   EXPECT_EQ(static_cast<int32_t>(kReportBlock.cumulative_num_packets_lost),
@@ skipping 10 matching lines @@
   EXPECT_EQ(-1, stats.aec_quality_min);
   EXPECT_EQ(kEchoDelayMedian, stats.echo_delay_median_ms);
   EXPECT_EQ(kEchoDelayStdDev, stats.echo_delay_std_ms);
   EXPECT_EQ(kEchoReturnLoss, stats.echo_return_loss);
   EXPECT_EQ(kEchoReturnLossEnhancement, stats.echo_return_loss_enhancement);
   EXPECT_EQ(kResidualEchoLikelihood, stats.residual_echo_likelihood);
   EXPECT_FALSE(stats.typing_noise_detected);
 }
 
 TEST(AudioSendStreamTest, GetStatsTypingNoiseDetected) {
-  ConfigHelper helper(false);
+  ConfigHelper helper(false, true);
   internal::AudioSendStream send_stream(
       helper.config(), helper.audio_state(), helper.worker_queue(),
       helper.packet_router(), helper.congestion_controller(),
       helper.bitrate_allocator(), helper.event_log(), helper.rtcp_rtt_stats());
   helper.SetupMockForGetStats();
   EXPECT_FALSE(send_stream.GetStats().typing_noise_detected);
 
   internal::AudioState* internal_audio_state =
       static_cast<internal::AudioState*>(helper.audio_state().get());
   VoiceEngineObserver* voe_observer =
       static_cast<VoiceEngineObserver*>(internal_audio_state);
   voe_observer->CallbackOnError(-1, VE_TYPING_NOISE_WARNING);
   EXPECT_TRUE(send_stream.GetStats().typing_noise_detected);
   voe_observer->CallbackOnError(-1, VE_TYPING_NOISE_OFF_WARNING);
   EXPECT_FALSE(send_stream.GetStats().typing_noise_detected);
 }
 
-TEST(AudioSendStreamTest, SendCodecAppliesConfigParams) {
-  ConfigHelper helper(false);
+TEST(AudioSendStreamTest, SendCodecAppliesNetworkAdaptor) {
+  ConfigHelper helper(false, true);
   auto stream_config = helper.config();
-  const CodecInst kOpusCodec = {111, "opus", 48000, 960, 2, 64000};
-  stream_config.send_codec_spec.codec_inst = kOpusCodec;
-  stream_config.send_codec_spec.enable_codec_fec = true;
-  stream_config.send_codec_spec.enable_opus_dtx = true;
-  stream_config.send_codec_spec.opus_max_playback_rate = 12345;
-  stream_config.send_codec_spec.cng_plfreq = 16000;
-  stream_config.send_codec_spec.cng_payload_type = 105;
-  stream_config.send_codec_spec.min_ptime_ms = 10;
-  stream_config.send_codec_spec.max_ptime_ms = 60;
+  stream_config.send_codec_spec =
+      rtc::Optional<AudioSendStream::Config::SendCodecSpec>({0, kOpusFormat});
   stream_config.audio_network_adaptor_config =
       rtc::Optional<std::string>("abced");
-  EXPECT_CALL(*helper.channel_proxy(), SetCodecFECStatus(true))
-      .WillOnce(Return(true));
-  EXPECT_CALL(
-      *helper.channel_proxy(),
-      SetOpusDtx(stream_config.send_codec_spec.enable_opus_dtx))
-      .WillOnce(Return(true));
-  EXPECT_CALL(
-      *helper.channel_proxy(),
-      SetOpusMaxPlaybackRate(
-          stream_config.send_codec_spec.opus_max_playback_rate))
-      .WillOnce(Return(true));
-  EXPECT_CALL(*helper.channel_proxy(),
-              SetSendCNPayloadType(
-                  stream_config.send_codec_spec.cng_payload_type,
-                  webrtc::kFreq16000Hz))
-      .WillOnce(Return(true));
-  EXPECT_CALL(
-      *helper.channel_proxy(),
-      SetReceiverFrameLengthRange(stream_config.send_codec_spec.min_ptime_ms,
-                                  stream_config.send_codec_spec.max_ptime_ms));
-  EXPECT_CALL(
-      *helper.channel_proxy(),
-      EnableAudioNetworkAdaptor(*stream_config.audio_network_adaptor_config));
+
+  EXPECT_CALL(helper.mock_encoder_factory(), MakeAudioEncoderMock(_, _, _))
+      .WillOnce(Invoke([](int payload_type, const SdpAudioFormat& format,
+                          std::unique_ptr<AudioEncoder>* return_value) {
+        auto mock_encoder = SetupAudioEncoderMock(payload_type, format);
+        EXPECT_CALL(*mock_encoder.get(), EnableAudioNetworkAdaptor(_, _, _))
+            .WillOnce(Return(true));
+        *return_value = std::move(mock_encoder);
+      }));
+
   internal::AudioSendStream send_stream(
       stream_config, helper.audio_state(), helper.worker_queue(),
       helper.packet_router(), helper.congestion_controller(),
       helper.bitrate_allocator(), helper.event_log(), helper.rtcp_rtt_stats());
 }
 
 // VAD is applied when codec is mono and the CNG frequency matches the codec
-// sample rate.
+// clock rate.
 TEST(AudioSendStreamTest, SendCodecCanApplyVad) {
-  ConfigHelper helper(false);
+  ConfigHelper helper(false, false);
   auto stream_config = helper.config();
-  const CodecInst kG722Codec = {9, "g722", 8000, 160, 1, 16000};
-  stream_config.send_codec_spec.codec_inst = kG722Codec;
-  stream_config.send_codec_spec.cng_plfreq = 8000;
-  stream_config.send_codec_spec.cng_payload_type = 105;
-  EXPECT_CALL(*helper.channel_proxy(), SetVADStatus(true))
-      .WillOnce(Return(true));
+  stream_config.send_codec_spec =
+      rtc::Optional<AudioSendStream::Config::SendCodecSpec>({9, kG722Format});
+  stream_config.send_codec_spec->cng_payload_type = rtc::Optional<int>(105);
+  using ::testing::Invoke;
+  std::unique_ptr<AudioEncoder> stolen_encoder;
+  EXPECT_CALL(*helper.channel_proxy(), SetEncoderForMock(_, _))
+      .WillOnce(
+          Invoke([&stolen_encoder](int payload_type,
+                                   std::unique_ptr<AudioEncoder>* encoder) {
+            stolen_encoder = std::move(*encoder);
+            return true;
+          }));
+
   internal::AudioSendStream send_stream(
       stream_config, helper.audio_state(), helper.worker_queue(),
       helper.packet_router(), helper.congestion_controller(),
       helper.bitrate_allocator(), helper.event_log(), helper.rtcp_rtt_stats());
+
+  // We cannot truly determine if the encoder created is an AudioEncoderCng.  It
+  // is the only reasonable implementation that will return something from
+  // ReclaimContainedEncoders, though.
+  ASSERT_TRUE(stolen_encoder);
+  EXPECT_FALSE(stolen_encoder->ReclaimContainedEncoders().empty());
 }
 
 TEST(AudioSendStreamTest, DoesNotPassHigherBitrateThanMaxBitrate) {
-  ConfigHelper helper(false);
+  ConfigHelper helper(false, true);
   internal::AudioSendStream send_stream(
       helper.config(), helper.audio_state(), helper.worker_queue(),
       helper.packet_router(), helper.congestion_controller(),
       helper.bitrate_allocator(), helper.event_log(), helper.rtcp_rtt_stats());
   EXPECT_CALL(*helper.channel_proxy(),
               SetBitrate(helper.config().max_bitrate_bps, _));
   send_stream.OnBitrateUpdated(helper.config().max_bitrate_bps + 5000, 0.0, 50,
                                6000);
 }
 
 TEST(AudioSendStreamTest, ProbingIntervalOnBitrateUpdated) {
-  ConfigHelper helper(false);
+  ConfigHelper helper(false, true);
   internal::AudioSendStream send_stream(
       helper.config(), helper.audio_state(), helper.worker_queue(),
       helper.packet_router(), helper.congestion_controller(),
       helper.bitrate_allocator(), helper.event_log(), helper.rtcp_rtt_stats());
   EXPECT_CALL(*helper.channel_proxy(), SetBitrate(_, 5000));
   send_stream.OnBitrateUpdated(50000, 0.0, 50, 5000);
 }
 
+// Test that AudioSendStream doesn't recreate the encoder unnecessarily.
+TEST(AudioSendStreamTest, DontRecreateEncoder) {
+  ConfigHelper helper(false, false);
+  // WillOnce is (currently) the default used by ConfigHelper if asked to set an
+  // expectation for SetEncoder. Since this behavior is essential for this test
+  // to be correct, it's instead set-up manually here. Otherwise a simple change
+  // to ConfigHelper (say to WillRepeatedly) would silently make this test
+  // useless.
+  EXPECT_CALL(*helper.channel_proxy(), SetEncoderForMock(_, _))
+      .WillOnce(Return(true));
+
+  auto stream_config = helper.config();
+  stream_config.send_codec_spec =
+      rtc::Optional<AudioSendStream::Config::SendCodecSpec>({9, kG722Format});
+  stream_config.send_codec_spec->cng_payload_type = rtc::Optional<int>(105);
+  internal::AudioSendStream send_stream(
+      stream_config, helper.audio_state(), helper.worker_queue(),
+      helper.packet_router(), helper.congestion_controller(),
+      helper.bitrate_allocator(), helper.event_log(), helper.rtcp_rtt_stats());
+  send_stream.Reconfigure(stream_config);
+}
+
 }  // namespace test
 }  // namespace webrtc