Rework UMAHistogramHelper and StatisticsDeltaReader into [Chrome]HistogramTester.
Design Doc (Googlers Only):
https://docs.google.com/a/google.com/document/d/1RUY0BcxBppdkwFP3T8qbQmQStBRFGsLmuR4WuIXhiCA/edit
BUG=384011
TBR=timsteele@chromium.org
Review URL: https://codereview.chromium.org/379283002
Cr-Commit-Position: refs/heads/master@{#291207}
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@291207 0039d316-1c4b-4281-b951-d872f2087c98
CrOS-Libchrome-Original-Commit: e7e9c86c60b24fbd53aa567ba423531486447f65
diff --git a/base/test/histogram_tester.cc b/base/test/histogram_tester.cc
new file mode 100644
index 0000000..412059a
--- /dev/null
+++ b/base/test/histogram_tester.cc
@@ -0,0 +1,122 @@
+// Copyright 2014 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 "base/test/histogram_tester.h"
+
+#include "base/metrics/histogram.h"
+#include "base/metrics/histogram_samples.h"
+#include "base/metrics/statistics_recorder.h"
+#include "base/stl_util.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace base {
+
+HistogramTester::HistogramTester() {
+ StatisticsRecorder::Initialize(); // Safe to call multiple times.
+
+ // Record any histogram data that exists when the object is created so it can
+ // be subtracted later.
+ StatisticsRecorder::Histograms histograms;
+ StatisticsRecorder::GetSnapshot(std::string(), &histograms);
+ for (size_t i = 0; i < histograms.size(); ++i) {
+ histograms_snapshot_[histograms[i]->histogram_name()] =
+ histograms[i]->SnapshotSamples().release();
+ }
+}
+
+HistogramTester::~HistogramTester() {
+ STLDeleteValues(&histograms_snapshot_);
+}
+
+void HistogramTester::ExpectUniqueSample(
+ const std::string& name,
+ base::HistogramBase::Sample sample,
+ base::HistogramBase::Count expected_count) const {
+ 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 HistogramTester::ExpectBucketCount(
+ const std::string& name,
+ base::HistogramBase::Sample sample,
+ base::HistogramBase::Count expected_count) const {
+ 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);
+ }
+}
+
+void HistogramTester::ExpectTotalCount(const std::string& name,
+ base::HistogramBase::Count count) const {
+ base::HistogramBase* histogram =
+ base::StatisticsRecorder::FindHistogram(name);
+ if (histogram) {
+ scoped_ptr<base::HistogramSamples> samples(histogram->SnapshotSamples());
+ CheckTotalCount(name, count, *samples);
+ } else {
+ // No histogram means there were zero samples.
+ EXPECT_EQ(count, 0) << "Histogram \"" << name << "\" does not exist.";
+ }
+}
+
+scoped_ptr<HistogramSamples> HistogramTester::GetHistogramSamplesSinceCreation(
+ const std::string& histogram_name) {
+ HistogramBase* histogram = StatisticsRecorder::FindHistogram(histogram_name);
+ if (!histogram)
+ return scoped_ptr<HistogramSamples>();
+ scoped_ptr<HistogramSamples> named_samples(histogram->SnapshotSamples());
+ HistogramSamples* named_original_samples =
+ histograms_snapshot_[histogram_name];
+ if (named_original_samples)
+ named_samples->Subtract(*named_original_samples);
+ return named_samples.Pass();
+}
+
+void HistogramTester::CheckBucketCount(
+ const std::string& name,
+ base::HistogramBase::Sample sample,
+ base::HistogramBase::Count expected_count,
+ base::HistogramSamples& samples) const {
+ int actual_count = samples.GetCount(sample);
+ std::map<std::string, HistogramSamples*>::const_iterator histogram_data;
+ histogram_data = histograms_snapshot_.find(name);
+ if (histogram_data != histograms_snapshot_.end())
+ actual_count -= histogram_data->second->GetCount(sample);
+
+ EXPECT_EQ(expected_count, actual_count)
+ << "Histogram \"" << name
+ << "\" does not have the right number of samples (" << expected_count
+ << ") in the expected bucket (" << sample << "). It has (" << actual_count
+ << ").";
+}
+
+void HistogramTester::CheckTotalCount(const std::string& name,
+ base::HistogramBase::Count expected_count,
+ base::HistogramSamples& samples) const {
+ int actual_count = samples.TotalCount();
+ std::map<std::string, HistogramSamples*>::const_iterator histogram_data;
+ histogram_data = histograms_snapshot_.find(name);
+ if (histogram_data != histograms_snapshot_.end())
+ actual_count -= histogram_data->second->TotalCount();
+
+ EXPECT_EQ(expected_count, actual_count)
+ << "Histogram \"" << name
+ << "\" does not have the right total number of samples ("
+ << expected_count << "). It has (" << actual_count << ").";
+}
+
+} // namespace base