Match only prefixes of histogram names.

base/test/histogram_tester_unittest.cc

 // Copyright 2014 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 "base/test/histogram_tester.h"
 
 #include <memory>
 
 #include "base/metrics/histogram_macros.h"
 #include "base/metrics/histogram_samples.h"
 #include "testing/gmock/include/gmock/gmock.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 using ::testing::ElementsAre;
 using ::testing::IsEmpty;
 
 namespace {
 
 const char kHistogram1[] = "Test1";
 const char kHistogram2[] = "Test2";
 const char kHistogram3[] = "Test3";
 const char kHistogram4[] = "Test4";
 const char kHistogram5[] = "Test5";
-const char kHistogramSuffix[] = "Test4.Test5";
+const char kHistogramSuffix[] = "Test4.Test5.Test6";
 
 }  // namespace
 
 namespace base {
 
 typedef testing::Test HistogramTesterTest;
 
 TEST_F(HistogramTesterTest, Scope) {
   // Record a histogram before the creation of the recorder.
   UMA_HISTOGRAM_BOOLEAN(kHistogram1, true);
@@ skipping 76 matching lines @@
 
   EXPECT_THAT(tester.GetAllSamples(kHistogram5),
               ElementsAre(Bucket(2, 1), Bucket(3, 2), Bucket(5, 1)));
 }
 
 TEST_F(HistogramTesterTest, TestGetAllSamples_NoSamples) {
   HistogramTester tester;
   EXPECT_THAT(tester.GetAllSamples(kHistogram5), IsEmpty());
 }
 
-// Wrong behaviour for GetTotalCountForPrefix: https://crbug.com/659977
-TEST_F(HistogramTesterTest, DISABLED_TestGetTotalCountsForPrefix) {
+TEST_F(HistogramTesterTest, TestGetTotalCountsForPrefix) {
   HistogramTester tester;
   UMA_HISTOGRAM_ENUMERATION(kHistogramSuffix, 2, 5);

[Ilya Sherman, 2017/01/12 20:32:41]

Optional nit: I think it would be clearer to inline the constant value here,
since anyone reading this test will need to know what the constant value is to
understand the checks below.

[pkalinnikov, 2017/01/13 10:28:59]

Done.

 
-  EXPECT_TRUE(tester.GetTotalCountsForPrefix("Test5").empty());
+  // Regression check for bug https://crbug.com/659977.
+  EXPECT_TRUE(tester.GetTotalCountsForPrefix("Test5.").empty());
+
+  EXPECT_EQ(1u, tester.GetTotalCountsForPrefix("Test4.").size());
 }
 
 }  // namespace base