Serialize/Deserialize support in HistogramBase

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/histogram_base.h"
 #include "base/metrics/sample_map.h"
 #include "base/metrics/sparse_histogram.h"
+#include "base/pickle.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"));
+  scoped_ptr<SparseHistogram> histogram(NewSparseHistogram("Sparse"));
   scoped_ptr<HistogramSamples> snapshot(histogram->SnapshotSamples());
   EXPECT_EQ(0, snapshot->TotalCount());
   EXPECT_EQ(0, snapshot->sum());
 
   histogram->Add(100);
   scoped_ptr<HistogramSamples> snapshot1(histogram->SnapshotSamples());
   EXPECT_EQ(1, snapshot1->TotalCount());
   EXPECT_EQ(1, snapshot1->GetCount(100));
 
   histogram->Add(100);
   histogram->Add(101);
   scoped_ptr<HistogramSamples> snapshot2(histogram->SnapshotSamples());
   EXPECT_EQ(3, snapshot2->TotalCount());
   EXPECT_EQ(2, snapshot2->GetCount(100));
   EXPECT_EQ(1, snapshot2->GetCount(101));
 }
 
+TEST_F(SparseHistogramTest, Serialize) {
+  scoped_ptr<SparseHistogram> histogram(NewSparseHistogram("Sparse"));
+  histogram->SetFlags(HistogramBase::kIPCSerializationSourceFlag);
+
+  Pickle pickle;
+  histogram->SerializeInfo(&pickle);
+
+  PickleIterator iter(pickle);
+
+  int type;
+  EXPECT_TRUE(iter.ReadInt(&type));
+  EXPECT_EQ(SPARSE_HISTOGRAM, type);
+
+  std::string name;
+  EXPECT_TRUE(iter.ReadString(&name));
+  EXPECT_EQ("Sparse", name);
+
+  int flag;
+  EXPECT_TRUE(iter.ReadInt(&flag));
+  EXPECT_EQ(HistogramBase::kIPCSerializationSourceFlag, flag);
+
+  // No more data in the pickle.
+  EXPECT_FALSE(iter.SkipBytes(1));
+}

[Ilya Sherman, 2012/12/29 00:17:30]

It seems like a more fruitful test would be to test that you can serialize a
histogram and deserialize it back to its original form.  There's currently no
test coverage for the deserialization code...

[kaiwang, 2013/01/08 00:51:40]

All deserializing tests are in histogram_base_unittests.cc (because the
deserialize function is there).
I added a TODO. Because currently SparseHistogram is not supported by
StatisticsRecorder, it's hard to test.

+
 }  // namespace base