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 93 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*());

[henrika_webrtc, 2016/11/02 10:02:06]

It is not clear to me why this method was added in the main interface. Is it
essential to mock it?

[aleloi, 2016/11/08 11:46:41]

I am now accessing the AudioDevice from the constructor of AudioState: one
AudioTransportProxy gets replaced with another one.

When an AudioState is constructed in a unit test, the default behavior was to
pass a mock VoiceEngine with an unmocked audio_device_module(), which returns
nullptr.

One way to solve it is to have a special case for when |device| is nullptr in
AudioState. That would lead to more conditional branches of execution and more
complex code, so we decided to change the tests by providing a mock VoE in which
audio_device_module returns a mock audio device.

I also plan to write more unit tests for AudioState which will test the new
functionality by using the audio_device_module.

   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_