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116 lines
4.5 KiB
C++
116 lines
4.5 KiB
C++
// Copyright 2014 The Chromium Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#ifndef BASE_TEST_HISTOGRAM_TESTER_H_
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#define BASE_TEST_HISTOGRAM_TESTER_H_
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#include <map>
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#include <ostream>
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#include <string>
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#include <utility>
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#include <vector>
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#include "base/basictypes.h"
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#include "base/memory/scoped_ptr.h"
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#include "base/metrics/histogram.h"
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#include "base/metrics/histogram_base.h"
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namespace base {
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struct Bucket;
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class HistogramSamples;
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// HistogramTester provides a simple interface for examining histograms, UMA
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// or otherwise. Tests can use this interface to verify that histogram data is
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// getting logged as intended.
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class HistogramTester {
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public:
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// The constructor will call StatisticsRecorder::Initialize() for you. Also,
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// this takes a snapshot of all current histograms counts.
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HistogramTester();
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~HistogramTester();
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// We know the exact number of samples in a bucket, and that no other bucket
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// should have samples. Measures the diff from the snapshot taken when this
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// object was constructed.
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void ExpectUniqueSample(const std::string& name,
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base::HistogramBase::Sample sample,
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base::HistogramBase::Count expected_count) const;
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// We know the exact number of samples in a bucket, but other buckets may
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// have samples as well. Measures the diff from the snapshot taken when this
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// object was constructed.
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void ExpectBucketCount(const std::string& name,
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base::HistogramBase::Sample sample,
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base::HistogramBase::Count expected_count) const;
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// We don't know the values of the samples, but we know how many there are.
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// This measures the diff from the snapshot taken when this object was
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// constructed.
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void ExpectTotalCount(const std::string& name,
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base::HistogramBase::Count count) const;
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// Returns a list of all of the buckets recorded since creation of this
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// object, as vector<Bucket>, where the Bucket represents the min boundary of
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// the bucket and the count of samples recorded to that bucket since creation.
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//
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// Example usage, using gMock:
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// EXPECT_THAT(histogram_tester.GetAllSamples("HistogramName"),
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// ElementsAre(Bucket(1, 5), Bucket(2, 10), Bucket(3, 5)));
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//
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// If you build the expected list programmatically, you can use ContainerEq:
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// EXPECT_THAT(histogram_tester.GetAllSamples("HistogramName"),
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// ContainerEq(expected_buckets));
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//
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// or EXPECT_EQ if you prefer not to depend on gMock, at the expense of a
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// slightly less helpful failure message:
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// EXPECT_EQ(expected_buckets,
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// histogram_tester.GetAllSamples("HistogramName"));
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std::vector<Bucket> GetAllSamples(const std::string& name);
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// Access a modified HistogramSamples containing only what has been logged
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// to the histogram since the creation of this object.
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scoped_ptr<HistogramSamples> GetHistogramSamplesSinceCreation(
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const std::string& histogram_name);
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private:
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// Verifies and asserts that value in the |sample| bucket matches the
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// |expected_count|. The bucket's current value is determined from |samples|
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// and is modified based on the snapshot stored for histogram |name|.
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void CheckBucketCount(const std::string& name,
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base::HistogramBase::Sample sample,
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base::Histogram::Count expected_count,
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const base::HistogramSamples& samples) const;
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// Verifies that the total number of values recorded for the histogram |name|
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// is |expected_count|. This is checked against |samples| minus the snapshot
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// that was taken for |name|.
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void CheckTotalCount(const std::string& name,
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base::Histogram::Count expected_count,
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const base::HistogramSamples& samples) const;
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// Used to determine the histogram changes made during this instance's
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// lifecycle. This instance takes ownership of the samples, which are deleted
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// when the instance is destroyed.
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std::map<std::string, HistogramSamples*> histograms_snapshot_;
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DISALLOW_COPY_AND_ASSIGN(HistogramTester);
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};
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struct Bucket {
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Bucket(base::HistogramBase::Sample min, base::HistogramBase::Count count)
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: min(min), count(count) {}
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bool operator==(const Bucket& other) const;
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base::HistogramBase::Sample min;
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base::HistogramBase::Count count;
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};
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void PrintTo(const Bucket& value, std::ostream* os);
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} // namespace base
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#endif // BASE_TEST_HISTOGRAM_TESTER_H_
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