chrome/test/base/uma_histogram_helper.cc

// Copyright (c) 2012 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 "chrome/test/base/uma_histogram_helper.h"

#include "base/bind.h"
#include "base/metrics/statistics_recorder.h"
#include "base/test/test_timeouts.h"
#include "chrome/test/base/ui_test_utils.h"
#include "content/public/browser/histogram_fetcher.h"

UMAHistogramHelper::UMAHistogramHelper() {
}

void UMAHistogramHelper::Fetch() {
  base::Closure callback = base::Bind(&UMAHistogramHelper::FetchCallback,
                                      base::Unretained(this));

  content::FetchHistogramsAsynchronously(
      base::MessageLoop::current(),
      callback,
      // If this call times out, it means that a child process is not
      // responding, which is something we should not ignore.  The timeout is
      // set to be longer than the normal browser test timeout so that it will
      // be prempted by the normal timeout.
      TestTimeouts::action_max_timeout() * 2);
  content::RunMessageLoop();
}

void UMAHistogramHelper::ExpectUniqueSample(
    const std::string& name,
    base::HistogramBase::Sample sample,
    base::HistogramBase::Count expected_count) {
  base::HistogramBase* histogram =
      base::StatisticsRecorder::FindHistogram(name);
  EXPECT_NE(static_cast<base::HistogramBase*>(NULL), histogram)
      << "Histogram \"" << name << "\" does not exist.";

  if (histogram) {
    scoped_ptr<base::HistogramSamples> samples(histogram->SnapshotSamples());
    CheckBucketCount(name, sample, expected_count, *samples);
    CheckTotalCount(name, expected_count, *samples);
  }
}

void UMAHistogramHelper::ExpectTotalCount(
    const std::string& name,
    base::HistogramBase::Count count) {
  base::HistogramBase* histogram =
      base::StatisticsRecorder::FindHistogram(name);
  EXPECT_NE(static_cast<base::HistogramBase*>(NULL), histogram)
      << "Histogram \"" << name << "\" does not exist.";

  if (histogram) {
    scoped_ptr<base::HistogramSamples> samples(histogram->SnapshotSamples());
    CheckTotalCount(name, count, *samples);
  }
}

void UMAHistogramHelper::FetchCallback() {
  base::MessageLoopForUI::current()->Quit();
}

void UMAHistogramHelper::CheckBucketCount(
    const std::string& name,
    base::HistogramBase::Sample sample,
    base::HistogramBase::Count expected_count,
    base::HistogramSamples& samples) {
  EXPECT_EQ(expected_count, samples.GetCount(sample))
      << "Histogram \"" << name
      << "\" does not have the right number of samples (" << expected_count
      << ") in the expected bucket (" << sample << ").";
}

void UMAHistogramHelper::CheckTotalCount(
    const std::string& name,
    base::HistogramBase::Count expected_count,
    base::HistogramSamples& samples) {
  EXPECT_EQ(expected_count, samples.TotalCount())
      << "Histogram \"" << name
      << "\" does not have the right total number of samples ("
      << expected_count << ").";
}