Rework UMAHistogramHelper and StatisticsDeltaReader into [Chrome]HistogramTester.

base/test/histogram_tester_unittest.cc

Index: base/test/histogram_tester_unittest.cc
diff --git a/base/test/statistics_delta_reader_unittest.cc b/base/test/histogram_tester_unittest.cc
similarity index 76%
rename from base/test/statistics_delta_reader_unittest.cc
rename to base/test/histogram_tester_unittest.cc
index 55180d115d1fd22ca1ce07192b3fc6004f35e456..0f61ad8a9368164a9eaa916269ac290f36688e7e 100644
--- a/base/test/statistics_delta_reader_unittest.cc
+++ b/base/test/histogram_tester_unittest.cc
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#include "base/test/statistics_delta_reader.h"
+#include "base/test/histogram_tester.h"
 
 #include "base/memory/scoped_ptr.h"
 #include "base/metrics/histogram.h"
@@ -11,22 +11,22 @@
 
 namespace base {
 
-TEST(StatisticsDeltaReaderTest, Scope) {
+TEST(HistogramTesterTest, Scope) {
   // Record a histogram before the creation of the recorder.
   UMA_HISTOGRAM_BOOLEAN("Test", true);
 
-  StatisticsDeltaReader reader;
+  HistogramTester tester;
 
   // Verify that no histogram is recorded.
   scoped_ptr<HistogramSamples> samples(
-      reader.GetHistogramSamplesSinceCreation("Test"));
+      tester.GetBaseHistogramSamples("Test"));
   EXPECT_FALSE(samples);
 
   // Record a histogram after the creation of the recorder.
   UMA_HISTOGRAM_BOOLEAN("Test", true);
 
   // Verify that one histogram is recorded.
-  samples = reader.GetHistogramSamplesSinceCreation("Test");
+  samples = tester.GetBaseHistogramSamples("Test");
   EXPECT_TRUE(samples);
   EXPECT_EQ(1, samples->TotalCount());
 }

[Ilya Sherman, 2014/07/15 03:56:35]

Please add test coverage for the other methods in the public API as well.

[Mike Lerman, 2014/07/16 17:29:03]

Done. I can add tests that will succeed, (e.g. log a 1, test for a 1), but I
don't think there's a way in GTest if I want an EXPECT_* to fail (e.g. log a 2,
call "ExpectUniqueSample" looking for 1), which means I can only test happy
paths.