talk/base/rollingaccumulator_unittest.cc

/*
 * libjingle
 * Copyright 2011, Google Inc.
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 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
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#include "talk/base/gunit.h"
#include "talk/base/rollingaccumulator.h"

namespace talk_base {

static bool IsApproximate(double expected, double value, double eps) {
  return expected - eps <= value && value <= expected + eps;
}

TEST(RollingAccumulatorTest, TestZeroSamples) {
  RollingAccumulator<int> accum(10);

  EXPECT_EQ(0, accum.count());
  EXPECT_EQ(0, accum.ComputeMean());
  EXPECT_EQ(0, accum.ComputeVariance());
}

TEST(RollingAccumulatorTest, TestSomeSamples) {
  RollingAccumulator<int> accum(10);
  for (int i = 0; i < 4; ++i) {
    accum.AddSample(i);
  }

  EXPECT_EQ(4, accum.count());
  EXPECT_EQ(6, accum.ComputeSum());
  EXPECT_EQ(1, accum.ComputeMean());
  EXPECT_EQ(1, accum.ComputeVariance());
}

TEST(RollingAccumulatorTest, TestRollingSamples) {
  RollingAccumulator<int> accum(10);
  for (int i = 0; i < 12; ++i) {
    accum.AddSample(i);
  }

  EXPECT_EQ(10, accum.count());
  EXPECT_EQ(65, accum.ComputeSum());
  EXPECT_EQ(6, accum.ComputeMean());
  EXPECT_TRUE(IsApproximate(9, accum.ComputeVariance(), 1));
}

TEST(RollingAccumulatorTest, TestRollingSamplesDouble) {
  RollingAccumulator<double> accum(10);
  for (int i = 0; i < 23; ++i) {
    accum.AddSample(5 * i);
  }

  EXPECT_EQ(10, accum.count());
  EXPECT_TRUE(IsApproximate(875.0, accum.ComputeSum(), 1E-6));
  EXPECT_TRUE(IsApproximate(87.5, accum.ComputeMean(), 1E-6));
  EXPECT_TRUE(IsApproximate(229.166667, accum.ComputeVariance(), 25));
}

}  // namespace talk_base