Add algorithm for Residual Echo Detector.

webrtc/modules/audio_processing/echo_detector/sliding_window_minimum_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 "webrtc/modules/audio_processing/echo_detector/sliding_window_minimum.h"
+
+#include <algorithm>
+
+#include "webrtc/base/random.h"
+#include "webrtc/test/gtest.h"
+
+namespace webrtc {
+
+TEST(SlidingWindowMinimumTests, HandMadeTest) {
+  SlidingWindowMinimum min_calculator(3);
+  min_calculator.AddValue(3);
+  EXPECT_EQ(0ul, min_calculator.GetMinimum());
+  min_calculator.AddValue(0);
+  EXPECT_EQ(0ul, min_calculator.GetMinimum());
+  min_calculator.AddValue(7);
+  EXPECT_EQ(0ul, min_calculator.GetMinimum());
+  min_calculator.AddValue(8);
+  EXPECT_EQ(0ul, min_calculator.GetMinimum());
+  min_calculator.AddValue(2);
+  EXPECT_EQ(2ul, min_calculator.GetMinimum());
+  min_calculator.AddValue(11);
+  EXPECT_EQ(2ul, min_calculator.GetMinimum());
+  min_calculator.AddValue(10);
+  EXPECT_EQ(2ul, min_calculator.GetMinimum());
+  min_calculator.AddValue(1);
+  EXPECT_EQ(1ul, min_calculator.GetMinimum());
+  min_calculator.AddValue(2);
+  EXPECT_EQ(1ul, min_calculator.GetMinimum());
+  min_calculator.AddValue(0);
+  EXPECT_EQ(0ul, min_calculator.GetMinimum());
+  min_calculator.AddValue(6);
+  EXPECT_EQ(0ul, min_calculator.GetMinimum());
+  min_calculator.AddValue(1);
+  EXPECT_EQ(0ul, min_calculator.GetMinimum());
+  min_calculator.AddValue(7);
+  EXPECT_EQ(1ul, min_calculator.GetMinimum());
+  min_calculator.AddValue(2);
+  EXPECT_EQ(1ul, min_calculator.GetMinimum());
+  min_calculator.AddValue(8);
+  EXPECT_EQ(2ul, min_calculator.GetMinimum());
+}
+
+TEST(SlidingWindowMinimumTests, RandomTest) {
+  SlidingWindowMinimum min_calculator(10);
+  Random rng(123);
+  std::vector<size_t> latest_values(10);
+  size_t latest_values_index = 0;
+  for (size_t i = 0; i < 10000; i++) {
+    size_t next_number = static_cast<size_t>(rng.Rand(10000));
+    min_calculator.AddValue(next_number);
+    latest_values[latest_values_index] = next_number;
+    size_t actual_minimum =
+        *std::min_element(latest_values.begin(), latest_values.end());
+    EXPECT_EQ(actual_minimum, min_calculator.GetMinimum());
+    ++latest_values_index;
+    latest_values_index %= 10;
+  }
+}
+
+}  // namespace webrtc