components/metrics/histogram_encoder_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 "components/metrics/histogram_encoder.h"
   6
   7 #include <string>
   8
   9 #include "base/basictypes.h"
  10 #include "base/metrics/bucket_ranges.h"
  11 #include "base/metrics/sample_vector.h"
  12 #include "testing/gtest/include/gtest/gtest.h"
  13
  14 namespace metrics {
  15
  16 TEST(HistogramEncoder, HistogramBucketFields) {
  17   // Create buckets: 1-5, 5-7, 7-8, 8-9, 9-10, 10-11, 11-12.
  18   base::BucketRanges ranges(8);
  19   ranges.set_range(0, 1);
  20   ranges.set_range(1, 5);
  21   ranges.set_range(2, 7);
  22   ranges.set_range(3, 8);
  23   ranges.set_range(4, 9);
  24   ranges.set_range(5, 10);
  25   ranges.set_range(6, 11);
  26   ranges.set_range(7, 12);
  27
  28   base::SampleVector samples(&ranges);
  29   samples.Accumulate(3, 1);   // Bucket 1-5.
  30   samples.Accumulate(6, 1);   // Bucket 5-7.
  31   samples.Accumulate(8, 1);   // Bucket 8-9. (7-8 skipped)
  32   samples.Accumulate(10, 1);  // Bucket 10-11. (9-10 skipped)
  33   samples.Accumulate(11, 1);  // Bucket 11-12.
  34
  35   ChromeUserMetricsExtension uma_proto;
  36   EncodeHistogramDelta("Test", samples, &uma_proto);
  37
  38   const HistogramEventProto& histogram_proto =
  39       uma_proto.histogram_event(uma_proto.histogram_event_size() - 1);
  40
  41   // Buckets with samples: 1-5, 5-7, 8-9, 10-11, 11-12.
  42   // Should become: 1-/, 5-7, /-9, 10-/, /-12.
  43   ASSERT_EQ(5, histogram_proto.bucket_size());
  44
  45   // 1-5 becomes 1-/ (max is same as next min).
  46   EXPECT_TRUE(histogram_proto.bucket(0).has_min());
  47   EXPECT_FALSE(histogram_proto.bucket(0).has_max());
  48   EXPECT_EQ(1, histogram_proto.bucket(0).min());
  49
  50   // 5-7 stays 5-7 (no optimization possible).
  51   EXPECT_TRUE(histogram_proto.bucket(1).has_min());
  52   EXPECT_TRUE(histogram_proto.bucket(1).has_max());
  53   EXPECT_EQ(5, histogram_proto.bucket(1).min());
  54   EXPECT_EQ(7, histogram_proto.bucket(1).max());
  55
  56   // 8-9 becomes /-9 (min is same as max - 1).
  57   EXPECT_FALSE(histogram_proto.bucket(2).has_min());
  58   EXPECT_TRUE(histogram_proto.bucket(2).has_max());
  59   EXPECT_EQ(9, histogram_proto.bucket(2).max());
  60
  61   // 10-11 becomes 10-/ (both optimizations apply, omit max is prioritized).
  62   EXPECT_TRUE(histogram_proto.bucket(3).has_min());
  63   EXPECT_FALSE(histogram_proto.bucket(3).has_max());
  64   EXPECT_EQ(10, histogram_proto.bucket(3).min());
  65
  66   // 11-12 becomes /-12 (last record must keep max, min is same as max - 1).
  67   EXPECT_FALSE(histogram_proto.bucket(4).has_min());
  68   EXPECT_TRUE(histogram_proto.bucket(4).has_max());
  69   EXPECT_EQ(12, histogram_proto.bucket(4).max());
  70 }
  71
  72 }  // namespace metrics