base/test/statistics_delta_reader_unittest.cc

   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/memory/scoped_ptr.h"
   6 #include "base/metrics/histogram.h"
   7 #include "base/metrics/histogram_samples.h"
   8 #include "base/metrics/statistics_recorder.h"
   9 #include "base/test/statistics_delta_reader.h"
  10 #include "testing/gtest/include/gtest/gtest.h"
  11
  12 namespace base {
  13
  14 class StatisticsDeltaReaderTest : public testing::Test {
  15  protected:
  16   virtual void SetUp() OVERRIDE {
  17     // Each test will have a clean state (no Histogram / BucketRanges
  18     // registered).
  19     statistics_recorder_ = new StatisticsRecorder();
  20   }
  21
  22   virtual void TearDown() OVERRIDE {
  23     delete statistics_recorder_;
  24     statistics_recorder_ = NULL;
  25   }
  26
  27   StatisticsRecorder* statistics_recorder_;
  28 };
  29
  30 TEST_F(StatisticsDeltaReaderTest, Scope) {
  31   // Record a histogram before the creation of the recorder.
  32   UMA_HISTOGRAM_BOOLEAN("Test", true);
  33
  34   StatisticsDeltaReader reader;
  35
  36   // Verify that no histogram is recorded.
  37   scoped_ptr<HistogramSamples> samples(
  38       reader.GetHistogramSamplesSinceCreation("Test"));
  39   EXPECT_TRUE(samples);
  40   EXPECT_EQ(0, samples->TotalCount());
  41
  42   // Record a histogram after the creation of the recorder.
  43   UMA_HISTOGRAM_BOOLEAN("Test", true);
  44
  45   // Verify that one histogram is recorded.
  46   samples = reader.GetHistogramSamplesSinceCreation("Test");
  47   EXPECT_TRUE(samples);
  48   EXPECT_EQ(1, samples->TotalCount());
  49 }
  50
  51 }  // namespace base