Match only prefixes of histogram names.

base/test/histogram_tester.h

 // 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.
 
 #ifndef BASE_TEST_HISTOGRAM_TESTER_H_
 #define BASE_TEST_HISTOGRAM_TESTER_H_
 
 #include <map>
 #include <memory>
 #include <ostream>
 #include <string>
 #include <utility>
 #include <vector>
 
 #include "base/macros.h"
 #include "base/metrics/histogram.h"
 #include "base/metrics/histogram_base.h"
 #include "base/time/time.h"
 
 namespace base {
 
 struct Bucket;
 class HistogramSamples;
 
 // HistogramTester provides a simple interface for examining histograms, UMA
 // or otherwise. Tests can use this interface to verify that histogram data is
 // getting logged as intended.
 class HistogramTester {
  public:
-  using CountsMap = std::map<std::string, base::HistogramBase::Count>;
+  using CountsMap = std::map<std::string, HistogramBase::Count>;
 
   // The constructor will call StatisticsRecorder::Initialize() for you. Also,
   // this takes a snapshot of all current histograms counts.
   HistogramTester();
   ~HistogramTester();
 
   // We know the exact number of samples in a bucket, and that no other bucket
   // should have samples. Measures the diff from the snapshot taken when this
   // object was constructed.
   void ExpectUniqueSample(const std::string& name,
-                          base::HistogramBase::Sample sample,
-                          base::HistogramBase::Count expected_count) const;
+                          HistogramBase::Sample sample,
+                          HistogramBase::Count expected_count) const;
 
   // We know the exact number of samples in a bucket, but other buckets may
   // have samples as well. Measures the diff from the snapshot taken when this
   // object was constructed.
   void ExpectBucketCount(const std::string& name,
-                         base::HistogramBase::Sample sample,
-                         base::HistogramBase::Count expected_count) const;
+                         HistogramBase::Sample sample,
+                         HistogramBase::Count expected_count) const;
 
   // We don't know the values of the samples, but we know how many there are.
   // This measures the diff from the snapshot taken when this object was
   // constructed.
   void ExpectTotalCount(const std::string& name,
-                        base::HistogramBase::Count count) const;
+                        HistogramBase::Count count) const;
 
   // We know exact number of samples for buckets corresponding to a time
   // interval. Other intervals may have samples too.
   void ExpectTimeBucketCount(const std::string& name,
-                             base::TimeDelta sample,
-                             base::HistogramBase::Count count) const;
+                             TimeDelta sample,
+                             HistogramBase::Count count) const;
 
   // Returns a list of all of the buckets recorded since creation of this
   // object, as vector<Bucket>, where the Bucket represents the min boundary of
   // the bucket and the count of samples recorded to that bucket since creation.
   //
   // Example usage, using gMock:
   //   EXPECT_THAT(histogram_tester.GetAllSamples("HistogramName"),
   //               ElementsAre(Bucket(1, 5), Bucket(2, 10), Bucket(3, 5)));
   //
   // If you build the expected list programmatically, you can use ContainerEq:
   //   EXPECT_THAT(histogram_tester.GetAllSamples("HistogramName"),
   //               ContainerEq(expected_buckets));
   //
   // or EXPECT_EQ if you prefer not to depend on gMock, at the expense of a
   // slightly less helpful failure message:
   //   EXPECT_EQ(expected_buckets,
   //             histogram_tester.GetAllSamples("HistogramName"));
   std::vector<Bucket> GetAllSamples(const std::string& name) const;
 
-  // Finds histograms whose names start with |query|, and returns them along
+  // Finds histograms whose names start with |prefix|, and returns them along
   // with the counts of any samples added since the creation of this object.
   // Histograms that are unchanged are omitted from the result. The return value
   // is a map whose keys are the histogram name, and whose values are the sample
   // count.
   //
   // This is useful for cases where the code under test is choosing among a
   // family of related histograms and incrementing one of them. Typically you
   // should pass the result of this function directly to EXPECT_THAT.
   //
   // Example usage, using gmock (which produces better failure messages):
   //   #include "testing/gmock/include/gmock/gmock.h"
   // ...
   //   base::HistogramTester::CountsMap expected_counts;
   //   expected_counts["MyMetric.A"] = 1;
   //   expected_counts["MyMetric.B"] = 1;
   //   EXPECT_THAT(histogram_tester.GetTotalCountsForPrefix("MyMetric."),
   //               testing::ContainerEq(expected_counts));
-  CountsMap GetTotalCountsForPrefix(const std::string& query) const;
+  CountsMap GetTotalCountsForPrefix(const std::string& prefix) const;
 
   // Access a modified HistogramSamples containing only what has been logged
   // to the histogram since the creation of this object.
   std::unique_ptr<HistogramSamples> GetHistogramSamplesSinceCreation(
       const std::string& histogram_name) const;
 
  private:
   // Verifies and asserts that value in the |sample| bucket matches the
   // |expected_count|. The bucket's current value is determined from |samples|
   // and is modified based on the snapshot stored for histogram |name|.
   void CheckBucketCount(const std::string& name,
-                        base::HistogramBase::Sample sample,
-                        base::Histogram::Count expected_count,
-                        const base::HistogramSamples& samples) const;
+                        HistogramBase::Sample sample,
+                        Histogram::Count expected_count,
+                        const HistogramSamples& samples) const;
 
   // Verifies that the total number of values recorded for the histogram |name|
   // is |expected_count|. This is checked against |samples| minus the snapshot
   // that was taken for |name|.
   void CheckTotalCount(const std::string& name,
-                       base::Histogram::Count expected_count,
-                       const base::HistogramSamples& samples) const;
+                       Histogram::Count expected_count,
+                       const HistogramSamples& samples) const;
 
   // Used to determine the histogram changes made during this instance's
   // lifecycle.
   std::map<std::string, std::unique_ptr<HistogramSamples>> histograms_snapshot_;
 
   DISALLOW_COPY_AND_ASSIGN(HistogramTester);
 };
 
 struct Bucket {
-  Bucket(base::HistogramBase::Sample min, base::HistogramBase::Count count)
+  Bucket(HistogramBase::Sample min, HistogramBase::Count count)
       : min(min), count(count) {}
 
   bool operator==(const Bucket& other) const;
 
-  base::HistogramBase::Sample min;
-  base::HistogramBase::Count count;
+  HistogramBase::Sample min;
+  HistogramBase::Count count;
 };
 
 void PrintTo(const Bucket& value, std::ostream* os);
 
 }  // namespace base
 
 #endif  // BASE_TEST_HISTOGRAM_TESTER_H_