Match only prefixes of histogram names.

base/test/histogram_tester_unittest.cc

Index: base/test/histogram_tester_unittest.cc
diff --git a/base/test/histogram_tester_unittest.cc b/base/test/histogram_tester_unittest.cc
index f896eaa3e89357abda627fee1d2f9d4b9fb52c0e..9ce39b9ac05711d05c661e646fe70f8da964848c 100644
--- a/base/test/histogram_tester_unittest.cc
+++ b/base/test/histogram_tester_unittest.cc
@@ -21,7 +21,7 @@ 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
 
@@ -118,12 +118,14 @@ TEST_F(HistogramTesterTest, TestGetAllSamples_NoSamples) {
   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