Injectable output rate calculater for AudioMixer.

webrtc/modules/audio_mixer/audio_mixer_impl_unittest.cc

Index: webrtc/modules/audio_mixer/audio_mixer_impl_unittest.cc
diff --git a/webrtc/modules/audio_mixer/audio_mixer_impl_unittest.cc b/webrtc/modules/audio_mixer/audio_mixer_impl_unittest.cc
index 517d9e5219cc2dbfa51e6a884972251115c6a116..e90dac1e70e9839f032da4db4f91b8eb0d002686 100644
--- a/webrtc/modules/audio_mixer/audio_mixer_impl_unittest.cc
+++ b/webrtc/modules/audio_mixer/audio_mixer_impl_unittest.cc
@@ -18,6 +18,7 @@
 #include "webrtc/base/bind.h"
 #include "webrtc/base/thread.h"
 #include "webrtc/modules/audio_mixer/audio_mixer_impl.h"
+#include "webrtc/modules/audio_mixer/default_output_rate_calculator.h"
 #include "webrtc/test/gmock.h"
 
 using testing::_;
@@ -85,6 +86,17 @@ class MockMixerAudioSource : public AudioMixer::Source {
   AudioFrameInfo fake_audio_frame_info_;
 };
 
+class CustomRateCalculator : public OutputRateCalculator {
+ public:
+  explicit CustomRateCalculator(int rate) : rate_(rate) {}
+  int CalculateOutputRate(const std::vector<int>& preferred_rates) {
+    return rate_;
+  }
+
+ private:
+  const int rate_;
+};
+
 // Creates participants from |frames| and |frame_info| and adds them
 // to the mixer. Compares mixed status with |expected_status|
 void MixAndCompare(
@@ -441,4 +453,30 @@ TEST(AudioMixer, UnmutedShouldMixBeforeLoud) {
 
   MixAndCompare(frames, frame_info, expected_status);
 }
+
+TEST(AudioMixer, MixingRateShouldBeDecidedByRateCalculator) {
+  constexpr int kOutputRate = 22000;
+  const auto mixer = AudioMixerImpl::CreateWithOutputRateCalculator(
+      std::unique_ptr<OutputRateCalculator>(
+          new CustomRateCalculator(kOutputRate)));
+  MockMixerAudioSource audio_source;
+  mixer->AddSource(&audio_source);
+  ResetFrame(audio_source.fake_frame());
+
+  EXPECT_CALL(audio_source, GetAudioFrameWithInfo(kOutputRate, _))
+      .Times(Exactly(1));
+
+  mixer->Mix(1, &frame_for_mixing);
+}
+
+TEST(AudioMixer, ZeroSourceRateShouldBeDecidedByRateCalculator) {
+  constexpr int kOutputRate = 8000;
+  const auto mixer = AudioMixerImpl::CreateWithOutputRateCalculator(
+      std::unique_ptr<OutputRateCalculator>(
+          new CustomRateCalculator(kOutputRate)));
+
+  mixer->Mix(1, &frame_for_mixing);
+
+  EXPECT_EQ(kOutputRate, frame_for_mixing.sample_rate_hz_);
+}
 }  // namespace webrtc