base/test/histogram_tester.cc

   1 // Copyright 2014 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 #include "base/test/histogram_tester.h"
   6
   7 #include "base/metrics/histogram.h"
   8 #include "base/metrics/histogram_samples.h"
   9 #include "base/metrics/statistics_recorder.h"
  10 #include "base/stl_util.h"
  11 #include "testing/gtest/include/gtest/gtest.h"
  12
  13 namespace base {
  14
  15 HistogramTester::HistogramTester() {
  16   StatisticsRecorder::Initialize();  // Safe to call multiple times.
  17
  18   // Record any histogram data that exists when the object is created so it can
  19   // be subtracted later.
  20   StatisticsRecorder::Histograms histograms;
  21   StatisticsRecorder::GetSnapshot(std::string(), &histograms);
  22   for (size_t i = 0; i < histograms.size(); ++i) {
  23     histograms_snapshot_[histograms[i]->histogram_name()] =
  24         histograms[i]->SnapshotSamples().release();
  25   }
  26 }
  27
  28 HistogramTester::~HistogramTester() {
  29   STLDeleteValues(&histograms_snapshot_);
  30 }
  31
  32 void HistogramTester::ExpectUniqueSample(
  33     const std::string& name,
  34     base::HistogramBase::Sample sample,
  35     base::HistogramBase::Count expected_count) const {
  36   base::HistogramBase* histogram =
  37       base::StatisticsRecorder::FindHistogram(name);
  38   EXPECT_NE(static_cast<base::HistogramBase*>(NULL), histogram)
  39       << "Histogram \"" << name << "\" does not exist.";
  40
  41   if (histogram) {
  42     scoped_ptr<base::HistogramSamples> samples(histogram->SnapshotSamples());
  43     CheckBucketCount(name, sample, expected_count, *samples);
  44     CheckTotalCount(name, expected_count, *samples);
  45   }
  46 }
  47
  48 void HistogramTester::ExpectBucketCount(
  49     const std::string& name,
  50     base::HistogramBase::Sample sample,
  51     base::HistogramBase::Count expected_count) const {
  52   base::HistogramBase* histogram =
  53       base::StatisticsRecorder::FindHistogram(name);
  54   EXPECT_NE(static_cast<base::HistogramBase*>(NULL), histogram)
  55       << "Histogram \"" << name << "\" does not exist.";
  56
  57   if (histogram) {
  58     scoped_ptr<base::HistogramSamples> samples(histogram->SnapshotSamples());
  59     CheckBucketCount(name, sample, expected_count, *samples);
  60   }
  61 }
  62
  63 void HistogramTester::ExpectTotalCount(const std::string& name,
  64                                        base::HistogramBase::Count count) const {
  65   base::HistogramBase* histogram =
  66       base::StatisticsRecorder::FindHistogram(name);
  67   if (histogram) {
  68     scoped_ptr<base::HistogramSamples> samples(histogram->SnapshotSamples());
  69     CheckTotalCount(name, count, *samples);
  70   } else {
  71     // No histogram means there were zero samples.
  72     EXPECT_EQ(count, 0) << "Histogram \"" << name << "\" does not exist.";
  73   }
  74 }
  75
  76 scoped_ptr<HistogramSamples> HistogramTester::GetHistogramSamplesSinceCreation(
  77     const std::string& histogram_name) {
  78   HistogramBase* histogram = StatisticsRecorder::FindHistogram(histogram_name);
  79   if (!histogram)
  80     return scoped_ptr<HistogramSamples>();
  81   scoped_ptr<HistogramSamples> named_samples(histogram->SnapshotSamples());
  82   HistogramSamples* named_original_samples =
  83       histograms_snapshot_[histogram_name];
  84   if (named_original_samples)
  85     named_samples->Subtract(*named_original_samples);
  86   return named_samples.Pass();
  87 }
  88
  89 void HistogramTester::CheckBucketCount(
  90     const std::string& name,
  91     base::HistogramBase::Sample sample,
  92     base::HistogramBase::Count expected_count,
  93     base::HistogramSamples& samples) const {
  94   int actual_count = samples.GetCount(sample);
  95   std::map<std::string, HistogramSamples*>::const_iterator histogram_data;
  96   histogram_data = histograms_snapshot_.find(name);
  97   if (histogram_data != histograms_snapshot_.end())
  98     actual_count -= histogram_data->second->GetCount(sample);
  99
 100   EXPECT_EQ(expected_count, actual_count)
 101       << "Histogram \"" << name
 102       << "\" does not have the right number of samples (" << expected_count
 103       << ") in the expected bucket (" << sample << "). It has (" << actual_count
 104       << ").";
 105 }
 106
 107 void HistogramTester::CheckTotalCount(const std::string& name,
 108                                       base::HistogramBase::Count expected_count,
 109                                       base::HistogramSamples& samples) const {
 110   int actual_count = samples.TotalCount();
 111   std::map<std::string, HistogramSamples*>::const_iterator histogram_data;
 112   histogram_data = histograms_snapshot_.find(name);
 113   if (histogram_data != histograms_snapshot_.end())
 114     actual_count -= histogram_data->second->TotalCount();
 115
 116   EXPECT_EQ(expected_count, actual_count)
 117       << "Histogram \"" << name
 118       << "\" does not have the right total number of samples ("
 119       << expected_count << "). It has (" << actual_count << ").";
 120 }
 121
 122 }  // namespace base