Create MemoryPressureStatsCollector.

components/memory_pressure/memory_pressure_stats_collector_unittest.cc

Index: components/memory_pressure/memory_pressure_stats_collector_unittest.cc
diff --git a/components/memory_pressure/memory_pressure_stats_collector_unittest.cc b/components/memory_pressure/memory_pressure_stats_collector_unittest.cc
new file mode 100644
index 0000000000000000000000000000000000000000..899d3de80c4d3bd12cc40c5cc02772c5c6815ee3
--- /dev/null
+++ b/components/memory_pressure/memory_pressure_stats_collector_unittest.cc
@@ -0,0 +1,143 @@
+// 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 "components/memory_pressure/memory_pressure_stats_collector.h"
+
+#include "base/test/simple_test_tick_clock.h"
+#include "testing/gmock/include/gmock/gmock.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace memory_pressure {
+
+// This is outside of the anonymous namespace as it is a friend to the class
+// under test.
+class TestMemoryPressureStatsCollector : public MemoryPressureStatsCollector {
+ public:
+  TestMemoryPressureStatsCollector(ReportingDelegate* reporting_delegate,
+                                   base::TickClock* tick_clock)
+      : MemoryPressureStatsCollector(reporting_delegate, tick_clock) {}
+
+  // Accessors.
+  base::TimeDelta unreported_cumulative_time(int i) const {
+    return unreported_cumulative_time_[i];
+  }
+  MemoryPressureLevel last_pressure_level() const {
+    return last_pressure_level_;
+  }
+  base::TimeTicks last_update_time() const { return last_update_time_; }
+};
+
+namespace {
+
+// A mock reporting delegate used in the unit test.
+class LenientMockReportingDelegate
+    : public MemoryPressureStatsCollector::ReportingDelegate {
+ public:
+  using MemoryPressureLevel = MemoryPressureListener::MemoryPressureLevel;
+
+  // ReportingDelegate:
+  MOCK_METHOD2(ReportCumulativeTime, void(MemoryPressureLevel, int));
+  MOCK_METHOD2(ReportLevelChange,
+               void(MemoryPressureLevel, MemoryPressureLevel));
+};
+using MockReportingDelegate = testing::StrictMock<LenientMockReportingDelegate>;
+
+// Test fixture.
+class MemoryPressureStatsCollectorTest : public testing::Test {
+ public:
+  MemoryPressureStatsCollectorTest()
+      : collector_(&reporting_delegate_, &tick_clock_) {}
+
+  void Tick(int ms) {
+    tick_clock_.Advance(base::TimeDelta::FromMilliseconds(ms));
+  }
+
+  TestMemoryPressureStatsCollector collector_;
+  MockReportingDelegate reporting_delegate_;
+  base::SimpleTestTickClock tick_clock_;
+};
+
+}  // namespace
+
+TEST_F(MemoryPressureStatsCollectorTest, EndToEnd) {
+  // Upon construction the last pressure level should be invalid.
+  EXPECT_NE(MemoryPressureListener::MEMORY_PRESSURE_LEVEL_NONE,
+            collector_.last_pressure_level());
+  EXPECT_NE(MemoryPressureListener::MEMORY_PRESSURE_LEVEL_MODERATE,
+            collector_.last_pressure_level());
+  EXPECT_NE(MemoryPressureListener::MEMORY_PRESSURE_LEVEL_CRITICAL,
+            collector_.last_pressure_level());
+
+  // And there should be no accumulated time at any pressure levels.
+  for (size_t i = 0; i < UMA_MEMORY_PRESSURE_LEVEL_COUNT; ++i)
+    EXPECT_TRUE(collector_.unreported_cumulative_time(i).is_zero());
+
+  // A first call should not invoke any reporting functions, but it should
+  // modify member variables.
+  Tick(500);
+  collector_.UpdateStatistics(
+      MemoryPressureListener::MEMORY_PRESSURE_LEVEL_NONE);
+  EXPECT_EQ(MemoryPressureListener::MEMORY_PRESSURE_LEVEL_NONE,
+            collector_.last_pressure_level());
+  EXPECT_EQ(tick_clock_.NowTicks(), collector_.last_update_time());
+  for (size_t i = 0; i < UMA_MEMORY_PRESSURE_LEVEL_COUNT; ++i)
+    EXPECT_TRUE(collector_.unreported_cumulative_time(i).is_zero());
+  testing::Mock::VerifyAndClearExpectations(&reporting_delegate_);
+
+  // A subsequent call with the same pressure level should increment the
+  // cumulative time but not make a report, as less than one second of time
+  // has been accumulated.
+  Tick(500);
+  collector_.UpdateStatistics(
+      MemoryPressureListener::MEMORY_PRESSURE_LEVEL_NONE);
+  EXPECT_EQ(MemoryPressureListener::MEMORY_PRESSURE_LEVEL_NONE,
+            collector_.last_pressure_level());
+  EXPECT_EQ(tick_clock_.NowTicks(), collector_.last_update_time());
+  EXPECT_EQ(base::TimeDelta::FromMilliseconds(500),
+            collector_.unreported_cumulative_time(0));
+  EXPECT_TRUE(collector_.unreported_cumulative_time(1).is_zero());
+  EXPECT_TRUE(collector_.unreported_cumulative_time(2).is_zero());
+  testing::Mock::VerifyAndClearExpectations(&reporting_delegate_);
+
+  // Yet another call and this time a report should be made, as one second
+  // of time has been accumulated. 500ms should remain unreported.
+  Tick(1000);
+  EXPECT_CALL(reporting_delegate_,
+              ReportCumulativeTime(
+                  MemoryPressureListener::MEMORY_PRESSURE_LEVEL_NONE, 1));
+  collector_.UpdateStatistics(
+      MemoryPressureListener::MEMORY_PRESSURE_LEVEL_NONE);
+  EXPECT_EQ(MemoryPressureListener::MEMORY_PRESSURE_LEVEL_NONE,
+            collector_.last_pressure_level());
+  EXPECT_EQ(tick_clock_.NowTicks(), collector_.last_update_time());
+  EXPECT_EQ(base::TimeDelta::FromMilliseconds(500),
+            collector_.unreported_cumulative_time(0));
+  EXPECT_TRUE(collector_.unreported_cumulative_time(1).is_zero());
+  EXPECT_TRUE(collector_.unreported_cumulative_time(2).is_zero());
+  testing::Mock::VerifyAndClearExpectations(&reporting_delegate_);
+
+  // A subsequent call with a different pressure level should increment the
+  // cumulative time and make several reports.
+  Tick(2250);
+  EXPECT_CALL(reporting_delegate_,
+              ReportCumulativeTime(
+                  MemoryPressureListener::MEMORY_PRESSURE_LEVEL_MODERATE, 2));
+  EXPECT_CALL(reporting_delegate_,
+              ReportLevelChange(
+                  MemoryPressureListener::MEMORY_PRESSURE_LEVEL_NONE,
+                  MemoryPressureListener::MEMORY_PRESSURE_LEVEL_MODERATE));
+  collector_.UpdateStatistics(
+      MemoryPressureListener::MEMORY_PRESSURE_LEVEL_MODERATE);
+  EXPECT_EQ(MemoryPressureListener::MEMORY_PRESSURE_LEVEL_MODERATE,
+            collector_.last_pressure_level());
+  EXPECT_EQ(tick_clock_.NowTicks(), collector_.last_update_time());
+  EXPECT_EQ(base::TimeDelta::FromMilliseconds(500),
+            collector_.unreported_cumulative_time(0));
+  EXPECT_EQ(base::TimeDelta::FromMilliseconds(250),
+            collector_.unreported_cumulative_time(1));
+  EXPECT_TRUE(collector_.unreported_cumulative_time(2).is_zero());
+  testing::Mock::VerifyAndClearExpectations(&reporting_delegate_);
+}
+
+}  // namespace memory_pressure