chrome/test/base/uma_histogram_helper.h

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef CHROME_TEST_BASE_UMA_HISTOGRAM_HELPER_H_
   6 #define CHROME_TEST_BASE_UMA_HISTOGRAM_HELPER_H_
   7
   8 #include "base/metrics/histogram.h"
   9 #include "base/metrics/histogram_base.h"
  10 #include "base/metrics/histogram_samples.h"
  11
  12 // UMAHistogramHelper provides a simple interface for examining UMA histograms.
  13 // Tests can use this interface to verify that UMA data is getting logged as
  14 // intended.
  15 class UMAHistogramHelper {
  16  public:
  17   UMAHistogramHelper();
  18
  19   // Each child process may have its own histogram data, make sure this data
  20   // gets accumulated into the browser process before we examine the histograms.
  21   void Fetch();
  22
  23   // We know the exact number of samples in a bucket, and that no other bucket
  24   // should have samples.
  25   void ExpectUniqueSample(const std::string& name,
  26                           base::HistogramBase::Sample sample,
  27                           base::HistogramBase::Count expected_count);
  28
  29   // We don't know the values of the samples, but we know how many there are.
  30   void ExpectTotalCount(const std::string& name,
  31                         base::HistogramBase::Count count);
  32
  33  private:
  34   void FetchCallback();
  35
  36   void CheckBucketCount(const std::string& name,
  37                         base::HistogramBase::Sample sample,
  38                         base::Histogram::Count expected_count,
  39                         base::HistogramSamples& samples);
  40
  41   void CheckTotalCount(const std::string& name,
  42                        base::Histogram::Count expected_count,
  43                        base::HistogramSamples& samples);
  44
  45   DISALLOW_COPY_AND_ASSIGN(UMAHistogramHelper);
  46 };
  47
  48 #endif  // CHROME_TEST_BASE_UMA_HISTOGRAM_HELPER_H_