Added test support to observe and verify UMA user actions during tests.

base/test/user_action_tester_unittest.cc

Index: base/test/user_action_tester_unittest.cc
diff --git a/base/test/user_action_tester_unittest.cc b/base/test/user_action_tester_unittest.cc
new file mode 100644
index 0000000000000000000000000000000000000000..88d07d0a15cc5af0f737376230d687eea6645b65
--- /dev/null
+++ b/base/test/user_action_tester_unittest.cc
@@ -0,0 +1,69 @@
+// Copyright 2015 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/user_action_tester.h"
+
+#include "base/metrics/user_metrics.h"
+#include "base/metrics/user_metrics_action.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace base {
+
+typedef testing::Test UserActionTesterTest;

[Ilya Sherman, 2015/04/08 20:49:19]

nit: Please omit this, and just use TEST rather than TEST_F

[bruthig, 2015/04/09 23:17:52]

Done.

+
+const char kUserAction1[] = "user.action.1";
+const char kUserAction2[] = "user.action.2";
+const char kUserAction3[] = "user.action.3";
+
+// Verify user action counts are zero initially.
+TEST_F(UserActionTesterTest, GetActionCountWhenNoActionsHaveBeenRecorded) {
+  UserActionTester user_action_tester;
+  EXPECT_EQ(0, user_action_tester.GetActionCount(kUserAction1));
+}
+
+// Verify user action counts are tracked properly.
+TEST_F(UserActionTesterTest, GetActionCountWhenActionsHaveBeenRecorded) {
+  UserActionTester user_action_tester;
+
+  user_action_tester.OnUserAction_for_test(kUserAction1);
+  user_action_tester.OnUserAction_for_test(kUserAction2);
+  user_action_tester.OnUserAction_for_test(kUserAction2);

[Ilya Sherman, 2015/04/08 20:49:19]

Rather than calling into the private method, please test the public interface,
i.e. recording user actions via base::RecordAction() and
base::RecordComputedAction().

[bruthig, 2015/04/09 23:17:52]

Done.

In this particular case I am somewhat indifferent about including the
base::RecordAction(...) in the scope of each and every test simply because the
the added code/time is minimal/negligible.  However, I'm not sure I would
totally agree with the statement 'only test the public interface'.  Perhaps we
could have a friendly debate offline on the subject?

[Ilya Sherman, 2015/04/09 23:49:35]

Happy to discuss offline, though I'm not sure either of us will really convince
the other to change our views ;)

+
+  EXPECT_EQ(1, user_action_tester.GetActionCount(kUserAction1));
+  EXPECT_EQ(2, user_action_tester.GetActionCount(kUserAction2));
+  EXPECT_EQ(0, user_action_tester.GetActionCount(kUserAction3));
+}
+
+// Verify no seg faults occur when resetting action counts when none have been
+// recorded.
+TEST_F(UserActionTesterTest, ResetCountsWhenNoActionsHaveBeenRecorded) {
+  UserActionTester user_action_tester;
+  user_action_tester.ResetCounts();
+}
+
+// Verify user action counts are set to zero on a ResetCounts.
+TEST_F(UserActionTesterTest, ResetCountsWhenActionsHaveBeenRecorded) {
+  UserActionTester user_action_tester;
+
+  user_action_tester.OnUserAction_for_test(kUserAction1);
+  user_action_tester.OnUserAction_for_test(kUserAction1);
+  user_action_tester.OnUserAction_for_test(kUserAction2);
+  user_action_tester.ResetCounts();
+
+  EXPECT_EQ(0, user_action_tester.GetActionCount(kUserAction1));
+  EXPECT_EQ(0, user_action_tester.GetActionCount(kUserAction2));
+  EXPECT_EQ(0, user_action_tester.GetActionCount(kUserAction3));
+}
+
+// Verify the UserActionsTester properly attaches to the global action
+// callbacks.
+TEST_F(UserActionTesterTest, VerifyUserActionTesterListensForUserActions) {
+  UserActionTester user_action_tester;
+
+  base::RecordAction(base::UserMetricsAction(kUserAction1));
+
+  EXPECT_EQ(1, user_action_tester.GetActionCount(kUserAction1));
+}
+
+}  // namespace base