Adding fraction of filter divergence in AEC metrics.

webrtc/modules/audio_processing/utility/block_fraction_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/block_fraction_calculator.h"
+
+namespace webrtc {
+
+TEST(BlockFractionCalculatorTest, Correctness) {
+  const size_t kBlockLength = 9;  // This has to be an odd number.
+  BlockFractionCalculator fraction_calculator(kBlockLength);
+  float reference = -1.0;
+
+  for (size_t i = 1; i < 3 * kBlockLength; ++i) {
+    EXPECT_EQ(reference, fraction_calculator.GetLatestFraction());
+    fraction_calculator.AddObservation(i % 2);
+
+    const bool end_of_block = i % kBlockLength == 0;
+    if (end_of_block) {
+      const float old_reference = reference;
+      // Fraction of even numbers in (i - kBlockLength + 1) ... i
+      reference = static_cast<float>((kBlockLength + (i % 2 ? 1 : 0)) / 2) /
+          kBlockLength;
+      // kBlockLength has to be an odd number to make fraction alternating.
+      EXPECT_NE(reference, old_reference);
+    }
+  }
+}
+
+TEST(BlockFractionCalculatorTest, Reset) {
+  const size_t kBlockLength = 9;
+  BlockFractionCalculator fraction_calculator(kBlockLength);
+  for (size_t i = 1; i < kBlockLength; ++i) {
+    fraction_calculator.AddObservation(i % 2);
+  }
+  fraction_calculator.Reset();
+  for (size_t i = 0; i < kBlockLength; ++i) {
+    fraction_calculator.AddObservation(i % 2);
+  }
+  EXPECT_EQ(fraction_calculator.GetLatestFraction(),
+            static_cast<float>(kBlockLength / 2) / kBlockLength);
+}
+
+}  // namespace webrtc