ACM: Adding unittests for the remixing functionality

On top of adding unittests for the remixing, the CL
moves the code tested to a separate file in order
to allow it to be tested.

Bug: webrtc:11007
Change-Id: I531736517bbcc715b3c1bf3a4256c42208c5b778
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/155740
Commit-Queue: Per Åhgren <peah@webrtc.org>
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#29839}
diff --git a/modules/audio_coding/acm2/acm_remixing_unittest.cc b/modules/audio_coding/acm2/acm_remixing_unittest.cc
new file mode 100644
index 0000000..a1a816f
--- /dev/null
+++ b/modules/audio_coding/acm2/acm_remixing_unittest.cc
@@ -0,0 +1,191 @@
+/*
+ *  Copyright (c) 2013 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 "modules/audio_coding/acm2/acm_remixing.h"
+
+#include <vector>
+
+#include "api/audio/audio_frame.h"
+#include "system_wrappers/include/clock.h"
+#include "test/gmock.h"
+#include "test/gtest.h"
+#include "test/testsupport/file_utils.h"
+
+using ::testing::AllOf;
+using ::testing::Each;
+using ::testing::ElementsAreArray;
+using ::testing::SizeIs;
+
+namespace webrtc {
+
+TEST(AcmRemixing, DownMixFrame) {
+  std::vector<int16_t> out(480, 0);
+  AudioFrame in;
+  in.num_channels_ = 2;
+  in.samples_per_channel_ = 480;
+
+  int16_t* const in_data = in.mutable_data();
+  for (size_t k = 0; k < in.samples_per_channel_; ++k) {
+    in_data[2 * k] = 2;
+    in_data[2 * k + 1] = 0;
+  }
+
+  DownMixFrame(in, out);
+
+  EXPECT_THAT(out, AllOf(SizeIs(480), Each(1)));
+}
+
+TEST(AcmRemixing, DownMixMutedFrame) {
+  std::vector<int16_t> out(480, 0);
+  AudioFrame in;
+  in.num_channels_ = 2;
+  in.samples_per_channel_ = 480;
+
+  int16_t* const in_data = in.mutable_data();
+  for (size_t k = 0; k < in.samples_per_channel_; ++k) {
+    in_data[2 * k] = 2;
+    in_data[2 * k + 1] = 0;
+  }
+
+  in.Mute();
+
+  DownMixFrame(in, out);
+
+  EXPECT_THAT(out, AllOf(SizeIs(480), Each(0)));
+}
+
+TEST(AcmRemixing, RemixMutedStereoFrameTo6Channels) {
+  std::vector<int16_t> out(480, 0);
+  AudioFrame in;
+  in.num_channels_ = 2;
+  in.samples_per_channel_ = 480;
+
+  int16_t* const in_data = in.mutable_data();
+  for (size_t k = 0; k < in.samples_per_channel_; ++k) {
+    in_data[2 * k] = 1;
+    in_data[2 * k + 1] = 2;
+  }
+  in.Mute();
+
+  ReMixFrame(in, 6, &out);
+  EXPECT_EQ(6 * 480u, out.size());
+
+  EXPECT_THAT(out, AllOf(SizeIs(in.samples_per_channel_ * 6), Each(0)));
+}
+
+TEST(AcmRemixing, RemixStereoFrameTo6Channels) {
+  std::vector<int16_t> out(480, 0);
+  AudioFrame in;
+  in.num_channels_ = 2;
+  in.samples_per_channel_ = 480;
+
+  int16_t* const in_data = in.mutable_data();
+  for (size_t k = 0; k < in.samples_per_channel_; ++k) {
+    in_data[2 * k] = 1;
+    in_data[2 * k + 1] = 2;
+  }
+
+  ReMixFrame(in, 6, &out);
+  EXPECT_EQ(6 * 480u, out.size());
+
+  std::vector<int16_t> expected_output(in.samples_per_channel_ * 6);
+  for (size_t k = 0; k < in.samples_per_channel_; ++k) {
+    expected_output[6 * k] = 1;
+    expected_output[6 * k + 1] = 2;
+  }
+
+  EXPECT_THAT(out, ElementsAreArray(expected_output));
+}
+
+TEST(AcmRemixing, RemixMonoFrameTo6Channels) {
+  std::vector<int16_t> out(480, 0);
+  AudioFrame in;
+  in.num_channels_ = 1;
+  in.samples_per_channel_ = 480;
+
+  int16_t* const in_data = in.mutable_data();
+  for (size_t k = 0; k < in.samples_per_channel_; ++k) {
+    in_data[k] = 1;
+  }
+
+  ReMixFrame(in, 6, &out);
+  EXPECT_EQ(6 * 480u, out.size());
+
+  std::vector<int16_t> expected_output(in.samples_per_channel_ * 6, 0);
+  for (size_t k = 0; k < in.samples_per_channel_; ++k) {
+    expected_output[6 * k] = 1;
+    expected_output[6 * k + 1] = 1;
+  }
+
+  EXPECT_THAT(out, ElementsAreArray(expected_output));
+}
+
+TEST(AcmRemixing, RemixStereoFrameToMono) {
+  std::vector<int16_t> out(480, 0);
+  AudioFrame in;
+  in.num_channels_ = 2;
+  in.samples_per_channel_ = 480;
+
+  int16_t* const in_data = in.mutable_data();
+  for (size_t k = 0; k < in.samples_per_channel_; ++k) {
+    in_data[2 * k] = 2;
+    in_data[2 * k + 1] = 0;
+  }
+
+  ReMixFrame(in, 1, &out);
+  EXPECT_EQ(480u, out.size());
+
+  EXPECT_THAT(out, AllOf(SizeIs(in.samples_per_channel_), Each(1)));
+}
+
+TEST(AcmRemixing, RemixMonoFrameToStereo) {
+  std::vector<int16_t> out(480, 0);
+  AudioFrame in;
+  in.num_channels_ = 1;
+  in.samples_per_channel_ = 480;
+
+  int16_t* const in_data = in.mutable_data();
+  for (size_t k = 0; k < in.samples_per_channel_; ++k) {
+    in_data[k] = 1;
+  }
+
+  ReMixFrame(in, 2, &out);
+  EXPECT_EQ(960u, out.size());
+
+  EXPECT_THAT(out, AllOf(SizeIs(2 * in.samples_per_channel_), Each(1)));
+}
+
+TEST(AcmRemixing, Remix3ChannelFrameToStereo) {
+  std::vector<int16_t> out(480, 0);
+  AudioFrame in;
+  in.num_channels_ = 3;
+  in.samples_per_channel_ = 480;
+
+  int16_t* const in_data = in.mutable_data();
+  for (size_t k = 0; k < in.samples_per_channel_; ++k) {
+    for (size_t j = 0; j < 3; ++j) {
+      in_data[3 * k + j] = j;
+    }
+  }
+
+  ReMixFrame(in, 2, &out);
+  EXPECT_EQ(2 * 480u, out.size());
+
+  std::vector<int16_t> expected_output(in.samples_per_channel_ * 2);
+  for (size_t k = 0; k < in.samples_per_channel_; ++k) {
+    for (size_t j = 0; j < 2; ++j) {
+      expected_output[2 * k + j] = static_cast<int>(j);
+    }
+  }
+
+  EXPECT_THAT(out, ElementsAreArray(expected_output));
+}
+
+}  // namespace webrtc