Add unit tests for sub-components of CaptureScheduler.

remoting/base/rate_counter_unittest.cc

+// Copyright 2013 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "remoting/base/rate_counter.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace remoting {
+
+static const int64 kTestValues[] = { 10, 20, 30, 10, 25, 16, 15 };
+
+// One second window and one sample per second, so rate equals each sample.
+TEST(RateCounterTest, OneSecondWindow) {
+  RateCounter rate_counter(base::TimeDelta::FromSeconds(1));
+  EXPECT_EQ(0, rate_counter.Rate());
+
+  base::Time now = base::Time::Now();
+  for (size_t i = 0; i < arraysize(kTestValues); ++i) {
+    now += base::TimeDelta::FromSeconds(1);
+    rate_counter.SetCurrentTimeForTest(now);
+    rate_counter.Record(kTestValues[i]);
+    EXPECT_EQ(static_cast<double>(kTestValues[i]), rate_counter.Rate());
+  }
+}
+
+// Record all samples instantaneously, so the rate is the total of the samples.
+TEST(RateCounterTest, OneSecondWindowAllSamples) {
+  RateCounter rate_counter(base::TimeDelta::FromSeconds(1));
+  EXPECT_EQ(0, rate_counter.Rate());
+
+  rate_counter.SetCurrentTimeForTest(base::Time::Now());
+
+  double expected = 0.0;
+  for (size_t i = 0; i < arraysize(kTestValues); ++i) {
+    rate_counter.Record(kTestValues[i]);
+    expected += kTestValues[i];
+  }
+
+  EXPECT_EQ(expected, rate_counter.Rate());
+}
+
+// Two second window, one sample per second.  For all but the first sample, the
+// rate should be the average of it and the preceding one.  For the first it
+// will be the average of the sample with zero.
+TEST(RateCounterTest, TwoSecondWindow) {
+  RateCounter rate_counter(base::TimeDelta::FromSeconds(2));
+  EXPECT_EQ(0, rate_counter.Rate());
+
+  base::Time now = base::Time::Now();
+  for (size_t i = 0; i < arraysize(kTestValues); ++i) {
+    now += base::TimeDelta::FromSeconds(1);
+    rate_counter.SetCurrentTimeForTest(now);
+    rate_counter.Record(kTestValues[i]);
+    double expected = kTestValues[i];
+    if (i > 0)
+      expected += kTestValues[i-1];
+    expected /= 2;
+    EXPECT_EQ(expected, rate_counter.Rate());
+  }
+}
+
+// Sample over a window one second shorter than the number of samples.
+// Rate should be the average of all but the first sample.
+TEST(RateCounterTest, LongWindow) {
+  const size_t kWindowSeconds = arraysize(kTestValues) - 1;
+
+  RateCounter rate_counter(base::TimeDelta::FromSeconds(kWindowSeconds));
+  EXPECT_EQ(0, rate_counter.Rate());
+
+  double expected = 0.0;
+  base::Time now = base::Time::Now();
+  for (size_t i = 1; i < arraysize(kTestValues); ++i) {

[alexeypa (please no reviews), 2013/03/19 23:36:55]

nit: I guess kTestValues[0] should also be recorded but not added to |expected|.

[Wez, 2013/03/20 00:17:27]

Done.

+    now += base::TimeDelta::FromSeconds(1);
+    rate_counter.SetCurrentTimeForTest(now);
+    rate_counter.Record(kTestValues[i]);
+    expected += kTestValues[i];
+  }
+  expected /= kWindowSeconds;
+
+  EXPECT_EQ(expected, rate_counter.Rate());
+}
+
+}  // namespace remoting