Chrome tracing for system-wide performance stats.

base/debug/trace_event_system_stats_monitor_unittest.cc

+// Copyright 2013 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/debug/trace_event_system_stats_monitor.h"
+
+#include <sstream>
+#include <string>
+
+#include "base/debug/trace_event_impl.h"
+#include "base/message_loop/message_loop.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace base {
+namespace debug {
+
+// Tests for the system stats monitor.
+// Exists as a class so it can be a friend of TraceEventSystemStatsMonitor.
+class TraceSystemStatsMonitorTest : public testing::Test {
+ public:
+  TraceSystemStatsMonitorTest() {}
+  virtual ~TraceSystemStatsMonitorTest() {}
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(TraceSystemStatsMonitorTest);
+};
+
+//////////////////////////////////////////////////////////////////////////////
+
+TEST_F(TraceSystemStatsMonitorTest, TraceEventSystemStatsMonitor) {
+  MessageLoop message_loop;
+
+  // Start with no observers of the TraceLog.
+  EXPECT_EQ(0u, TraceLog::GetInstance()->GetObserverCountForTest());
+
+  // Creating a system stats monitor adds it to the TraceLog observer list.
+  scoped_ptr<TraceEventSystemStatsMonitor> system_stats_monitor(
+      new TraceEventSystemStatsMonitor(
+          message_loop.message_loop_proxy()));
+  EXPECT_EQ(1u, TraceLog::GetInstance()->GetObserverCountForTest());
+  EXPECT_TRUE(
+      TraceLog::GetInstance()->HasEnabledStateObserver(
+          system_stats_monitor.get()));
+
+  // By default the observer isn't dumping memory profiles.
+  EXPECT_FALSE(system_stats_monitor->IsTimerRunningForTest());
+
+  // Simulate enabling tracing.
+  system_stats_monitor->StartProfiling();
+  message_loop.RunUntilIdle();
+  EXPECT_TRUE(system_stats_monitor->IsTimerRunningForTest());
+
+  // Simulate disabling tracing.
+  system_stats_monitor->StopProfiling();
+  message_loop.RunUntilIdle();
+  EXPECT_FALSE(system_stats_monitor->IsTimerRunningForTest());
+
+  // Deleting the observer removes it from the TraceLog observer list.
+  system_stats_monitor.reset();
+  EXPECT_EQ(0u, TraceLog::GetInstance()->GetObserverCountForTest());
+}
+
+}  // namespace debug
+}  // namespace base