Added an empty AudioTransportProxy to AudioState.

webrtc/test/mock_voice_engine.h

 /*
  *  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.
  */
 
@@ skipping 17 matching lines @@
   // methods don't use any override declarations, and we want to avoid
   // warnings from -Winconsistent-missing-override. See
   // http://crbug.com/428099.
   MockVoiceEngine(
       rtc::scoped_refptr<AudioDecoderFactory> decoder_factory = nullptr)
       : decoder_factory_(decoder_factory) {
     // Increase ref count so this object isn't automatically deleted whenever
     // interfaces are Release():d.
     ++_ref_count;
     // We add this default behavior to make the mock easier to use in tests. It
     // will create a NiceMock of a voe::ChannelProxy.

[the sun, 2016/11/09 09:41:53]

How about we do the same for ADM, APM and transport? The would reduce clutter in
the unit tests and you could remove the null checks in AudioTransportProxy.

ON_CALL(*this, audio_, audio_processing())
    .WillByDefault(testing::Return(&mock_audio_processing));

...

testing::NiceMock<webrtc::test::MockAudioProcessing> mock_audio_processing;

[aleloi, 2016/11/09 16:37:01]

Acknowledged.

     // TODO(ossu): As long as AudioReceiveStream is implmented as a wrapper
     // around Channel, we need to make sure ChannelProxy returns the same
     // decoder factory as the one passed in when creating an AudioReceiveStream.
     ON_CALL(*this, ChannelProxyFactory(testing::_))
         .WillByDefault(testing::Invoke([this](int channel_id) {
           auto* proxy =
               new testing::NiceMock<webrtc::test::MockVoEChannelProxy>();
           EXPECT_CALL(*proxy, GetAudioDecoderFactory())
               .WillRepeatedly(testing::ReturnRef(decoder_factory_));
           return proxy;
@@ skipping 55 matching lines @@
 
   // VoEBase
   MOCK_METHOD1(RegisterVoiceEngineObserver, int(VoiceEngineObserver& observer));
   MOCK_METHOD0(DeRegisterVoiceEngineObserver, int());
   MOCK_METHOD3(
       Init,
       int(AudioDeviceModule* external_adm,
           AudioProcessing* audioproc,
           const rtc::scoped_refptr<AudioDecoderFactory>& decoder_factory));
   MOCK_METHOD0(audio_processing, AudioProcessing*());
+  MOCK_METHOD0(audio_device_module, AudioDeviceModule*());
   MOCK_METHOD0(Terminate, int());
   MOCK_METHOD0(CreateChannel, int());
   MOCK_METHOD1(CreateChannel, int(const ChannelConfig& config));
   MOCK_METHOD1(DeleteChannel, int(int channel));
   MOCK_METHOD1(StartReceive, int(int channel));
   MOCK_METHOD1(StopReceive, int(int channel));
   MOCK_METHOD1(StartPlayout, int(int channel));
   MOCK_METHOD1(StopPlayout, int(int channel));
   MOCK_METHOD1(StartSend, int(int channel));
   MOCK_METHOD1(StopSend, int(int channel));
@@ skipping 204 matching lines @@
   // functor implementing the default version of ChannelProxyFactory, above.
   // GMock creates an unfortunate copy of the functor, which would cause us to
   // return a dangling reference. Fortunately, this should go away once
   // voe::Channel does.
   rtc::scoped_refptr<AudioDecoderFactory> decoder_factory_;
 };
 }  // namespace test
 }  // namespace webrtc
 
 #endif  // WEBRTC_AUDIO_MOCK_VOICE_ENGINE_H_