Skeleton code of SparseHistogram

base/metrics/sparse_histogram_unittest.cc

+// Copyright (c) 2012 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.
+
+#include <string>
+
+#include "base/memory/scoped_ptr.h"
+#include "base/metrics/sparse_histogram.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace base {
+
+class SparseHistogramTest : public testing::Test {
+ protected:
+  scoped_ptr<SparseHistogram> NewSparseHistogram(const std::string& name) {
+    return scoped_ptr<SparseHistogram>(new SparseHistogram(name));
+  }
+};
+
+TEST_F(SparseHistogramTest, BasicTest) {
+  scoped_ptr<SparseHistogram> histogram(NewSparseHistogram("Sparse1"));
+  std::map<HistogramBase::Sample, HistogramBase::Count> sample;
+  histogram->SnapshotSample(&sample);
+
+  ASSERT_EQ(0u, sample.size());
+
+  histogram->Add(100);
+  histogram->SnapshotSample(&sample);
+  ASSERT_EQ(1u, sample.size());
+  EXPECT_EQ(1, sample[100]);
+
+  histogram->Add(100);
+  histogram->Add(101);
+  histogram->SnapshotSample(&sample);
+  ASSERT_EQ(2u, sample.size());
+  EXPECT_EQ(2, sample[100]);
+  EXPECT_EQ(1, sample[101]);
+}
+
+}  // namespace base