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 };
+
+TEST(RateCounterTest, OneSecondWindow) {

[alexeypa (please no reviews), 2013/03/18 19:39:39]

nit: Add the case when Record() is never called.

[Wez, 2013/03/19 23:23:14]

Done.

+  base::Time now = base::Time::Now();
+
+  RateCounter rate_counter(base::TimeDelta::FromSeconds(1));
+  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());
+  }
+}
+
+TEST(RateCounterTest, TwoSecondWindow) {
+  base::Time now = base::Time::Now();
+
+  RateCounter rate_counter(base::TimeDelta::FromSeconds(2));
+  for (size_t i = 0; i < arraysize(kTestValues); ++i) {
+    now += base::TimeDelta::FromSeconds(1);
+    rate_counter.SetCurrentTimeForTest(now);
+    rate_counter.Record(kTestValues[i]);
+    if (i > 0) {
+      double expected = kTestValues[i] + kTestValues[i-1];
+      expected /= 2;
+      EXPECT_EQ(expected, rate_counter.Rate());

[alexeypa (please no reviews), 2013/03/18 19:39:39]

nit: Verify the result of Rate() when |i| is 0 as well.

[Wez, 2013/03/19 23:23:14]

Done.

+    }
+  }
+}
+
+TEST(RateCounterTest, LongWindow) {
+  base::Time now = base::Time::Now();
+
+  const size_t kWindowSeconds = arraysize(kTestValues) + 1;

[alexeypa (please no reviews), 2013/03/18 19:39:39]

I guess it is better to have kWindowsSeconds = arraysize(kTestValues) and do not
add kTestValues[0] to |expected| to emphasize that the time window is (now -
time_window, now]. I.e. it includes |now| but does not include |now -
time_window|.

It is even better to explain that in the comment in front of  RateCounter to
give an idea how it works.

[Wez, 2013/03/19 23:23:14]

I've reworded the comments and updated this test to have an N-1 length window.

+
+  RateCounter rate_counter(base::TimeDelta::FromSeconds(kWindowSeconds));
+  double expected = 0.0;
+  for (size_t i = 0; i < arraysize(kTestValues); ++i) {
+    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