third_party/WebKit/Source/platform/HistogramTest.cpp

// Copyright 2016 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 "platform/Histogram.h"

#include "base/metrics/histogram_samples.h"
#include "testing/gtest/include/gtest/gtest.h"

namespace blink {

class ScopedUsHistogramTimerTest : public ::testing::Test {
public:
    static void advanceClock(double microseconds)
    {
        s_timeElapsed += microseconds;
    }

protected:
    static double returnMockTime()
    {
        return s_timeElapsed;
    }

    virtual void SetUp()
    {
        s_timeElapsed = 0.0;
        m_originalTimeFunction = setTimeFunctionsForTesting(returnMockTime);
    }

    virtual void TearDown()
    {
        setTimeFunctionsForTesting(m_originalTimeFunction);
    }

private:
    static double s_timeElapsed;
    TimeFunction m_originalTimeFunction;
};

double ScopedUsHistogramTimerTest::s_timeElapsed;

class TestCustomCountHistogram : public CustomCountHistogram {
public:
    TestCustomCountHistogram(const char* name, base::HistogramBase::Sample min, base::HistogramBase::Sample max, int32_t bucketCount)
    : CustomCountHistogram(name, min, max, bucketCount) {}

    base::HistogramBase* histogram() { return m_histogram; }
};

TEST_F(ScopedUsHistogramTimerTest, Basic)
{
    TestCustomCountHistogram scopedUsCounter("test", 0, 10000000, 50);
    {
        ScopedUsHistogramTimer timer(scopedUsCounter);
        advanceClock(0.5);
    }
    // 0.5s == 500000us
    EXPECT_EQ(500000, scopedUsCounter.histogram()->SnapshotSamples()->sum());
}

} // namespace blink