Merge multiple histogram snapshots into single one for reporting.

base/metrics/histogram_unittest.cc

Index: base/metrics/histogram_unittest.cc
diff --git a/base/metrics/histogram_unittest.cc b/base/metrics/histogram_unittest.cc
index 09f9106d09758837ce79ac15453bb5c198a3b9d8..c1202aa4732752c60b52be770ba9de6719ace331 100644
--- a/base/metrics/histogram_unittest.cc
+++ b/base/metrics/histogram_unittest.cc
@@ -29,11 +29,13 @@
 namespace base {
 
 class HistogramTest : public testing::Test {
+ public:
+  HistogramTest() {}
+  ~HistogramTest() override {}
+
  protected:
   const int32_t kAllocatorMemorySize = 64 << 10;  // 64 KiB
 
-  HistogramTest() {}
-
   void SetUp() override {
     // Each test will have a clean state (no Histogram / BucketRanges
     // registered).
@@ -50,6 +52,7 @@ class HistogramTest : public testing::Test {
   }
 
   void InitializeStatisticsRecorder() {
+    StatisticsRecorder::ResetForTesting();
     statistics_recorder_ = new StatisticsRecorder();
   }
 
@@ -84,6 +87,21 @@ class HistogramTest : public testing::Test {
   DISALLOW_COPY_AND_ASSIGN(HistogramTest);
 };
 
+class AllocatorHistogramTest : public HistogramTest,
+                               public testing::WithParamInterface<bool> {
+ public:
+  AllocatorHistogramTest() {
+    if (GetParam())
+      CreatePersistentMemoryAllocator();
+  }
+  ~AllocatorHistogramTest() override {}
+};
+
+// Run all AllocatorHistogramTest cases with both heap and persistent memory.
+INSTANTIATE_TEST_CASE_P(HeapAndPersistent, AllocatorHistogramTest,
+                        testing::Values(false, true));
+
+
 // Check for basic syntax and use.
 TEST_F(HistogramTest, BasicTest) {
   // Try basic construction
@@ -208,6 +226,35 @@ TEST_F(HistogramTest, NameMatchTest) {
   EXPECT_EQ(2, samples->GetCount(10));
 }
 
+// Check that delta calculations work correct.
+TEST_P(AllocatorHistogramTest, DeltaTest) {
+  HistogramBase* histogram =
+      Histogram::FactoryGet("DeltaHistogram", 1, 64, 8,
+                            HistogramBase::kNoFlags);
+  histogram->Add(1);
+  histogram->Add(10);
+  histogram->Add(50);
+
+  scoped_ptr<HistogramSamples> samples = histogram->SnapshotDelta();
+  EXPECT_EQ(3, samples->TotalCount());
+  EXPECT_EQ(1, samples->GetCount(1));
+  EXPECT_EQ(1, samples->GetCount(10));
+  EXPECT_EQ(1, samples->GetCount(50));
+  EXPECT_EQ(samples->TotalCount(), samples->redundant_count());
+
+  samples = histogram->SnapshotDelta();
+  EXPECT_EQ(0, samples->TotalCount());
+
+  histogram->Add(10);
+  histogram->Add(10);
+  samples = histogram->SnapshotDelta();
+  EXPECT_EQ(2, samples->TotalCount());
+  EXPECT_EQ(2, samples->GetCount(10));
+
+  samples = histogram->SnapshotDelta();
+  EXPECT_EQ(0, samples->TotalCount());
+}
+
 TEST_F(HistogramTest, ExponentialRangesTest) {
   // Check that we got a nice exponential when there was enough room.
   BucketRanges ranges(9);
@@ -520,7 +567,7 @@ TEST_F(HistogramTest, CorruptBucketBounds) {
 
   bucket_ranges->set_range(2, bucket_ranges->range(1));
   bucket_ranges->set_range(1, tmp);
-  EXPECT_EQ(0, histogram->FindCorruption(*snapshot));
+  EXPECT_EQ(0U, histogram->FindCorruption(*snapshot));
 
   // Show that two simple changes don't offset each other
   bucket_ranges->set_range(3, bucket_ranges->range(3) + 1);