Add algorithm for Residual Echo Detector.

webrtc/modules/audio_processing/echo_detector/mean_variance_estimator_unittest.cc

Index: webrtc/modules/audio_processing/echo_detector/mean_variance_estimator_unittest.cc
diff --git a/webrtc/modules/audio_processing/echo_detector/mean_variance_estimator_unittest.cc b/webrtc/modules/audio_processing/echo_detector/mean_variance_estimator_unittest.cc
new file mode 100644
index 0000000000000000000000000000000000000000..ec4350f45e77c5087fb574c94cb17ed087308e88
--- /dev/null
+++ b/webrtc/modules/audio_processing/echo_detector/mean_variance_estimator_unittest.cc
@@ -0,0 +1,64 @@
+
+/*
+ *  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 "webrtc/modules/audio_processing/echo_detector/mean_variance_estimator.h"
+#include "webrtc/test/gtest.h"
+
+namespace webrtc {
+
+TEST(MeanVarianceEstimatorTests, InsertTwoValues) {
+  MeanVarianceEstimator test_estimator;
+  // Insert two values.
+  test_estimator.Update(3.f);
+  test_estimator.Update(5.f);
+
+  EXPECT_GT(test_estimator.mean(), 0.f);
+  EXPECT_GT(test_estimator.std_deviation(), 0.f);
+  // Test Clear method
+  test_estimator.Clear();
+  EXPECT_EQ(test_estimator.mean(), 0.f);
+  EXPECT_EQ(test_estimator.std_deviation(), 0.f);
+}
+
+TEST(MeanVarianceEstimatorTests, InsertZeroes) {
+  MeanVarianceEstimator test_estimator;
+  // Insert the same value many times.
+  for (size_t i = 0; i < 10000; i++) {
+    test_estimator.Update(0.f);
+  }
+  EXPECT_EQ(test_estimator.mean(), 0.f);
+  EXPECT_EQ(test_estimator.std_deviation(), 0.f);
+}
+
+TEST(MeanVarianceEstimatorTests, ConstantValueTest) {
+  MeanVarianceEstimator test_estimator;
+  for (size_t i = 0; i < 10000; i++) {
+    test_estimator.Update(3.f);
+  }
+  // The mean should be close to three, and the standard deviation should be
+  // close to zero.
+  EXPECT_NEAR(3.0f, test_estimator.mean(), 0.01f);
+  EXPECT_NEAR(0.0f, test_estimator.std_deviation(), 0.01f);
+}
+
+TEST(MeanVarianceEstimatorTests, AlternatingValueTest) {
+  MeanVarianceEstimator test_estimator;
+  for (size_t i = 0; i < 10000; i++) {
+    test_estimator.Update(1.f);
+    test_estimator.Update(-1.f);
+  }
+  // The mean should be close to zero, and the standard deviation should be
+  // close to one.
+  EXPECT_NEAR(0.0f, test_estimator.mean(), 0.01f);
+  EXPECT_NEAR(1.0f, test_estimator.std_deviation(), 0.01f);
+}
+
+}  // namespace webrtc