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/memory/linked_ptr.h" 9 #include "base/metrics/histogram.h" 10 #include "base/metrics/histogram_base.h" 11 #include "base/metrics/histogram_samples.h" 12 13 // UMAHistogramHelper provides a simple interface for examining UMA histograms. 14 // Tests can use this interface to verify that UMA data is getting logged as 15 // intended. 16 class UMAHistogramHelper { 17 public: 18 // UMAHistogramHelper should be created before the execution of the test case. 19 UMAHistogramHelper(); 20 21 ~UMAHistogramHelper(); 22 23 // Parameters should be string literals of all histograms to snapshot. 24 // Call this before executing the test code. This method can be called 25 // multiple times. The existing snapshots are preserved, except when one of 26 // the |histogram_names| was previously passed as a parameter, then a new 27 // snapshot will replace the existing one. 28 void PrepareSnapshot(const char* const histogram_names[], 29 size_t num_histograms); 30 31 // Each child process may have its own histogram data, make sure this data 32 // gets accumulated into the browser process before we examine the histograms. 33 void Fetch(); 34 35 // We know the exact number of samples in a bucket, and that no other bucket 36 // should have samples. If |PrepareSnapshot| was called for the histogram 37 // named |name| then the |expected_count| is the diff from the snapshot. 38 void ExpectUniqueSample(const std::string& name, 39 base::HistogramBase::Sample sample, 40 base::HistogramBase::Count expected_count); 41 42 // We know the exact number of samples in a bucket, but other buckets may 43 // have samples as well. If |PrepareSnapshot| was called for histogram named 44 // |name| then the |expected_count| is the diff from the snapshot. 45 void ExpectBucketCount(const std::string& name, 46 base::HistogramBase::Sample sample, 47 base::HistogramBase::Count expected_count); 48 49 // We don't know the values of the samples, but we know how many there are. If 50 // |PrepareSnapshot| was called for |name| histogram, then the 51 // |count| is the diff from the snapshot. 52 void ExpectTotalCount(const std::string& name, 53 base::HistogramBase::Count count); 54 55 private: 56 void FetchCallback(); 57 58 void CheckBucketCount(const std::string& name, 59 base::HistogramBase::Sample sample, 60 base::Histogram::Count expected_count, 61 base::HistogramSamples& samples); 62 63 void CheckTotalCount(const std::string& name, 64 base::Histogram::Count expected_count, 65 base::HistogramSamples& samples); 66 67 DISALLOW_COPY_AND_ASSIGN(UMAHistogramHelper); 68 69 // The map from histogram names to their snapshots 70 std::map<std::string, linked_ptr<base::HistogramSamples> > 71 histogram_snapshots; 72 }; 73 74 #endif // CHROME_TEST_BASE_UMA_HISTOGRAM_HELPER_H_ 75