Adding fraction of filter divergence in AEC metrics.

webrtc/modules/audio_processing/utility/mean_calculator_unittest.cc

+/*
+ *  Copyright (c) 2016 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 "testing/gtest/include/gtest/gtest.h"
+
+#include "webrtc/modules/audio_processing/utility/mean_calculator.h"
+
+namespace webrtc {
+
+TEST(MeanCalculatorTest, Correctness) {
+  const size_t kWindowLength = 10;
+  MeanCalculator mean_calculator(kWindowLength);
+  size_t i = 0;
+  for (; i < kWindowLength; ++i) {
+    EXPECT_FALSE(mean_calculator.IsWindowFull()) << i;
+    EXPECT_FALSE(mean_calculator.GetMean());
+    mean_calculator.AddSample(static_cast<float>(i));
+  }
+  for (; i < 3 * kWindowLength; ++i) {
+    EXPECT_TRUE(mean_calculator.IsWindowFull());
+    // (i - kWindowLength) ... (i - 1)
+    EXPECT_EQ(i - 0.5 * (1 + kWindowLength), *mean_calculator.GetMean());

[peah-webrtc, 2016/03/15 09:18:41]

The test tests the accuracy of the mean calculator only when integer values
(albeit cast to float) are used. I think you should add tests where
1) Values with nonzero fractions are stored.
2) Value of largely differing magnitudes are stored.
3) A large number of values are first processed stored in the calculator, and
then the correctness of the mean is verified after that (the mean should then be
equal to the mean of the kWindowLength values processed at the end.

+    mean_calculator.AddSample(static_cast<float>(i));
+  }
+}
+
+TEST(MeanCalculatorTest, Clear) {
+  const size_t kWindowLength = 10;
+  MeanCalculator mean_calculator(kWindowLength);
+  for (size_t i = 0; i < kWindowLength; ++i) {
+    mean_calculator.AddSample(static_cast<float>(i));
+  }
+  EXPECT_TRUE(mean_calculator.IsWindowFull());
+  mean_calculator.Clear();
+
+  for (size_t i = 0; i < kWindowLength; ++i) {
+    EXPECT_FALSE(mean_calculator.IsWindowFull());
+    EXPECT_FALSE(mean_calculator.GetMean());
+    mean_calculator.AddSample(static_cast<float>(i));
+  }
+  EXPECT_TRUE(mean_calculator.IsWindowFull());
+  EXPECT_EQ(0.5 * (kWindowLength - 1), *mean_calculator.GetMean());
+}
+
+}  // namespace webrt