Home | History | Annotate | Download | only in test 
      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
    123