Adding second layer of the echo canceller 3 functionality.

webrtc/modules/audio_processing/aec3/mock/mock_render_delay_buffer.h

+/*
+ *  Copyright (c) 2016 The WebRTC project authors. All Rights Reserved.

[hlundin-webrtc, 2017/01/18 13:08:49]

2017

[peah-webrtc, 2017/01/19 15:33:05]

Done.

+ *
+ *  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.
+ */
+
+#ifndef WEBRTC_MODULES_AUDIO_PROCESSING_AEC3_MOCK_MOCK_RENDER_DELAY_BUFFER_H_
+#define WEBRTC_MODULES_AUDIO_PROCESSING_AEC3_MOCK_MOCK_RENDER_DELAY_BUFFER_H_
+
+#include <vector>
+
+#include "webrtc/modules/audio_processing/aec3/aec3_constants.h"
+#include "webrtc/modules/audio_processing/aec3/render_delay_buffer.h"
+#include "webrtc/test/gmock.h"
+
+namespace webrtc {
+namespace test {
+
+class MockRenderDelayBuffer : public RenderDelayBuffer {
+ public:
+  explicit MockRenderDelayBuffer(int sample_rate_hz)
+      : block_(std::vector<std::vector<float>>(
+            NumBandsForRate(sample_rate_hz),
+            std::vector<float>(kBlockSize, 0.f))) {}
+  virtual ~MockRenderDelayBuffer() = default;
+
+  MOCK_METHOD1(Insert, bool(std::vector<std::vector<float>>* block));
+  virtual const std::vector<std::vector<float>>& GetNext() { return block_; }

[hlundin-webrtc, 2017/01/18 13:08:49]

I think the preferred pattern is to have the mock of the real method delegate to
a fake. See
https://github.com/google/googlemock/blob/master/googlemock/docs/CookBook.md#....

For a tangible example in WebRTC, see
webrtc/modules/audio_conference_mixer/test/audio_conference_mixer_unittest.cc,
line 36.

In your code, I would suggest the following. Mock GetNext as any other method:
MOCK_METHOD0(GetNext, const std::vector<std::vector<float>>&());

In the body of the mock's ctor, add:
ON_CALL(*this, GetNext())
        .WillByDefault(Invoke(this, &MockRenderDelayBuffer::FakeGetNext));

Finally, define a new method, private to the mock:
const std::vector<std::vector<float>>& FakeGetNext() { return block_; }

This way, you can still set expectations on GetNext being called (or not), but
it will by default return the fake block.

[peah-webrtc, 2017/01/19 15:33:05]

Great suggestion!!! Thanks!

Done.

+  MOCK_METHOD1(SetDelay, void(size_t delay));
+  MOCK_CONST_METHOD0(Delay, size_t());
+  MOCK_CONST_METHOD0(MaxDelay, size_t());
+  MOCK_CONST_METHOD0(IsBlockAvailable, bool());
+  MOCK_CONST_METHOD0(MaxApiJitter, size_t());
+
+ private:
+  std::vector<std::vector<float>> block_;
+};
+
+}  // namespace test
+}  // namespace webrtc
+
+#endif  // WEBRTC_MODULES_AUDIO_PROCESSING_AEC3_MOCK_MOCK_RENDER_DELAY_BUFFER_H_