Convert SessionLengthLimiter to OneShotTimer

chrome/browser/chromeos/power/session_length_limiter_unittest.cc

Index: chrome/browser/chromeos/power/session_length_limiter_unittest.cc
diff --git a/chrome/browser/chromeos/power/session_length_limiter_unittest.cc b/chrome/browser/chromeos/power/session_length_limiter_unittest.cc
index 40a86bdb2d91e8c10569081125c7770621a79796..bf9a4778058441cb7afa4a91cb8703e4968cefc9 100644
--- a/chrome/browser/chromeos/power/session_length_limiter_unittest.cc
+++ b/chrome/browser/chromeos/power/session_length_limiter_unittest.cc
@@ -4,8 +4,9 @@
 
 #include "chrome/browser/chromeos/power/session_length_limiter.h"
 
-#include <deque>
+#include <queue>
 #include <utility>
+#include <vector>
 
 #include "base/callback.h"
 #include "base/compiler_specific.h"
@@ -16,16 +17,13 @@
 #include "base/single_thread_task_runner.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/thread_task_runner_handle.h"
-#include "base/time.h"
 #include "base/values.h"
-#include "chrome/browser/browser_process.h"
 #include "chrome/common/pref_names.h"
 #include "chrome/test/base/testing_browser_process.h"
 #include "chrome/test/base/testing_pref_service.h"
 #include "testing/gmock/include/gmock/gmock.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
-using ::testing::_;
 using ::testing::Invoke;
 using ::testing::Mock;
 using ::testing::NiceMock;
@@ -34,159 +32,197 @@ namespace chromeos {
 
 namespace {
 
-// The interval at which the SessionLengthLimiter checks whether the remaining
-// session time has reachzed zero.
-const base::TimeDelta kSessionLengthLimitTimerInterval(
-    base::TimeDelta::FromSeconds(1));
-
-const base::TimeDelta kZeroTimeDelta;
-const base::TimeDelta kTenSeconds(base::TimeDelta::FromSeconds(10));
-
 class MockSessionLengthLimiterDelegate : public SessionLengthLimiter::Delegate {
  public:
   MOCK_CONST_METHOD0(GetCurrentTime, const base::Time(void));
   MOCK_METHOD0(StopSession, void(void));
 };
 
-// A SingleThreadTaskRunner that allows the task queue to be inspected and
-// delayed tasks to be run without waiting for the actual delays to expire.
-class ImmediateSingleThreadTaskRunner : public base::SingleThreadTaskRunner {
+// A SingleThreadTaskRunner that mocks the current time and allows it to be
+// fast-forwarded.
+class MockTimeSingleThreadTaskRunner : public base::SingleThreadTaskRunner {
  public:
-  virtual bool RunsTasksOnCurrentThread() const OVERRIDE {
-    return true;
-  }
+  MockTimeSingleThreadTaskRunner();
 
+  // base::SingleThreadTaskRunner:
+  virtual bool RunsTasksOnCurrentThread() const OVERRIDE;
   virtual bool PostDelayedTask(const tracked_objects::Location& from_here,
                                const base::Closure& task,
-                               base::TimeDelta delay) OVERRIDE {
-    tasks_.push_back(std::pair<base::TimeDelta, base::Closure>(delay, task));
-    return true;
-  }
-
+                               base::TimeDelta delay) OVERRIDE;
   virtual bool PostNonNestableDelayedTask(
       const tracked_objects::Location& from_here,
       const base::Closure& task,
-      base::TimeDelta delay) OVERRIDE {
-    NOTREACHED();
-    return false;
-  }
+      base::TimeDelta delay) OVERRIDE;
 
-  void RunTasks() {
-    std::deque<std::pair<base::TimeDelta, base::Closure> > tasks;
-    tasks.swap(tasks_);
-    for (std::deque<std::pair<base::TimeDelta, base::Closure> >::iterator
-             it = tasks.begin(); it != tasks.end(); ++it) {
-      it->second.Run();
-    }
-  }
+  const base::Time& GetCurrentTime() const;
 
-  const std::deque<std::pair<base::TimeDelta, base::Closure> >& tasks() const {
-    return tasks_;
-  }
+  void FastForwardBy(int64 milliseconds);
+  void FastForwardUntilNoTasksRemain();
 
  private:
-  std::deque<std::pair<base::TimeDelta, base::Closure> > tasks_;
+  // Strict weak temporal ordering of tasks.
+  class TemporalOrder {
+   public:
+    bool operator()(
+        const std::pair<base::Time, base::Closure>& first_task,
+        const std::pair<base::Time, base::Closure>& second_task) const;
+  };
+
+  virtual ~MockTimeSingleThreadTaskRunner();
 
-  virtual ~ImmediateSingleThreadTaskRunner() {}
+  base::Time now_;
+  std::priority_queue<std::pair<base::Time, base::Closure>,
+                      std::vector<std::pair<base::Time, base::Closure> >,
+                      TemporalOrder> tasks_;
 };
 
 }  // namespace
 
 class SessionLengthLimiterTest : public testing::Test {
  protected:
-  SessionLengthLimiterTest() : delegate_(NULL) {
-  }
+  SessionLengthLimiterTest();
+
+  // testing::Test:
+  virtual void SetUp() OVERRIDE;
+  virtual void TearDown() OVERRIDE;
+
+  void SetSessionStartTimePref(int64 session_start_time);
+  void VerifySessionStartTimePref();
+  void SetSessionLengthLimitPref(int64 session_length_limit);
 
-  virtual void SetUp() {
-    TestingBrowserProcess::GetGlobal()->SetLocalState(&local_state_);
-    SessionLengthLimiter::RegisterPrefs(local_state_.registry());
+  void ExpectStopSession();
+  void CheckStopSessionTime();
 
-    delegate_ = new NiceMock<MockSessionLengthLimiterDelegate>;
-    ON_CALL(*delegate_, GetCurrentTime())
-        .WillByDefault(Invoke(this, &SessionLengthLimiterTest::GetCurrentTime));
-    EXPECT_CALL(*delegate_, StopSession()).Times(0);
-    runner_ = new ImmediateSingleThreadTaskRunner;
+  void CreateSessionLengthLimiter(bool browser_restarted);
 
+  TestingPrefServiceSimple local_state_;
+  scoped_refptr<MockTimeSingleThreadTaskRunner> runner_;
+  base::Time session_start_time_;
+  base::Time session_end_time_;
+
+  MockSessionLengthLimiterDelegate* delegate_;  // Owned by
+                                                // session_length_limiter_.
+  scoped_ptr<SessionLengthLimiter> session_length_limiter_;
+};
+
+MockTimeSingleThreadTaskRunner::MockTimeSingleThreadTaskRunner()
     // Initialize the mock clock to a fixed value, ensuring that timezone
     // differences or DST changes do not affect the test.
-    now_ = base::Time::UnixEpoch() + base::TimeDelta::FromDays(40 * 365);
-    session_start_time_ = now_;
-  }
+    : now_(base::Time::UnixEpoch() + base::TimeDelta::FromDays(40 * 365)) {
+}
 
-  virtual void TearDown() {
-    TestingBrowserProcess::GetGlobal()->SetLocalState(NULL);
-  }
+bool MockTimeSingleThreadTaskRunner::RunsTasksOnCurrentThread() const {
+  return true;
+}
 
-  void SetSessionStartTimePref(int64 session_start_time) {
-    local_state_.SetUserPref(prefs::kSessionStartTime,
-                             base::Value::CreateStringValue(
-                                 base::Int64ToString(session_start_time)));
-  }
+bool MockTimeSingleThreadTaskRunner::PostDelayedTask(
+    const tracked_objects::Location& from_here,
+    const base::Closure& task,
+    base::TimeDelta delay) {
+  tasks_.push(std::pair<base::Time, base::Closure>(now_ + delay, task));
+  return true;
+}
 
-  void VerifySessionStartTimePref() {
-    base::Time session_start_time(base::Time::FromInternalValue(
-        local_state_.GetInt64(prefs::kSessionStartTime)));
-    EXPECT_EQ(session_start_time_, session_start_time);
-  }
+bool MockTimeSingleThreadTaskRunner::PostNonNestableDelayedTask(
+    const tracked_objects::Location& from_here,
+    const base::Closure& task,
+    base::TimeDelta delay) {
+  NOTREACHED();
+  return false;
+}
 
-  void SetSessionLengthLimitPref(int64 session_length_limit) {
-    local_state_.SetUserPref(prefs::kSessionLengthLimit,
-                             base::Value::CreateIntegerValue(
-                                 session_length_limit));
-    base::TimeDelta remaining(
-          base::TimeDelta::FromMilliseconds(session_length_limit) -
-              (now_ - session_start_time_));
-      if (remaining < kZeroTimeDelta)
-        remaining = kZeroTimeDelta;
-    remaining_.reset(new base::TimeDelta(remaining));
-  }
+const base::Time& MockTimeSingleThreadTaskRunner::GetCurrentTime() const {
+  return now_;
+}
 
-  void ExpectStopSession() {
-    Mock::VerifyAndClearExpectations(delegate_);
-    EXPECT_CALL(*delegate_, StopSession()).Times(1);
+void MockTimeSingleThreadTaskRunner::FastForwardBy(int64 delta) {
+  const base::Time latest = now_ + base::TimeDelta::FromMilliseconds(delta);
+  while (!tasks_.empty() && tasks_.top().first <= latest) {
+    now_ = tasks_.top().first;
+    tasks_.top().second.Run();
+    tasks_.pop();
   }
+  now_ = latest;
+}
 
-  void CreateSessionLengthLimiter(bool browser_restarted) {
-    session_length_limiter_.reset(
-        new SessionLengthLimiter(delegate_, browser_restarted));
+void MockTimeSingleThreadTaskRunner::FastForwardUntilNoTasksRemain() {
+  while (!tasks_.empty()) {
+    now_ = tasks_.top().first;
+    tasks_.top().second.Run();
+    tasks_.pop();
   }
+}
 
-  void VerifyNoTimerTickIsEnqueued() {
-    EXPECT_TRUE(runner_->tasks().empty());
-  }
+bool MockTimeSingleThreadTaskRunner::TemporalOrder::operator()(
+    const std::pair<base::Time, base::Closure>& first_task,
+    const std::pair<base::Time, base::Closure>& second_task) const {
+  return first_task.first < second_task.first;
+}
 
-  void VerifyTimerTickIsEnqueued() {
-    ASSERT_EQ(1U, runner_->tasks().size());
-    EXPECT_EQ(kSessionLengthLimitTimerInterval,
-              runner_->tasks().front().first);
-  }
+MockTimeSingleThreadTaskRunner::~MockTimeSingleThreadTaskRunner() {
+}
 
-  void VerifyTimerTick() {
-    VerifyTimerTickIsEnqueued();
-    runner_->RunTasks();
+SessionLengthLimiterTest::SessionLengthLimiterTest() : delegate_(NULL) {
+}
 
-    now_ += kSessionLengthLimitTimerInterval;
-    *remaining_ -= kSessionLengthLimitTimerInterval;
-    if (*remaining_ < kZeroTimeDelta)
-      remaining_.reset(new base::TimeDelta(kZeroTimeDelta));
-  }
+void SessionLengthLimiterTest::SetUp() {
+  TestingBrowserProcess::GetGlobal()->SetLocalState(&local_state_);
+  SessionLengthLimiter::RegisterPrefs(local_state_.registry());
+  runner_ = new MockTimeSingleThreadTaskRunner;
+  session_start_time_ = runner_->GetCurrentTime();
+
+  delegate_ = new NiceMock<MockSessionLengthLimiterDelegate>;
+  ON_CALL(*delegate_, GetCurrentTime())
+      .WillByDefault(Invoke(runner_.get(),
+                            &MockTimeSingleThreadTaskRunner::GetCurrentTime));
+  EXPECT_CALL(*delegate_, StopSession()).Times(0);
+}
 
-  base::Time GetCurrentTime() const {
-    return now_;
-  }
+void SessionLengthLimiterTest::TearDown() {
+  TestingBrowserProcess::GetGlobal()->SetLocalState(NULL);
+}
 
-  TestingPrefServiceSimple local_state_;
-  MockSessionLengthLimiterDelegate* delegate_;  // Owned by
-                                                // session_length_limiter_.
-  scoped_refptr<ImmediateSingleThreadTaskRunner> runner_;
+void SessionLengthLimiterTest::SetSessionStartTimePref(
+    int64 session_start_time) {
+  local_state_.SetUserPref(prefs::kSessionStartTime,
+                           base::Value::CreateStringValue(
+                               base::Int64ToString(session_start_time)));
+}
 
-  base::Time session_start_time_;
-  base::Time now_;
-  scoped_ptr<base::TimeDelta> remaining_;
+void SessionLengthLimiterTest::VerifySessionStartTimePref() {
+  base::Time session_start_time(base::Time::FromInternalValue(
+      local_state_.GetInt64(prefs::kSessionStartTime)));
+  EXPECT_EQ(session_start_time_, session_start_time);
+}
 
-  scoped_ptr<SessionLengthLimiter> session_length_limiter_;
-};
+void SessionLengthLimiterTest::SetSessionLengthLimitPref(
+    int64 session_length_limit) {
+  session_end_time_ = session_start_time_ +
+      base::TimeDelta::FromMilliseconds(session_length_limit);
+  // If the new session end time has passed already, the session should end now.
+  if (session_end_time_ < runner_->GetCurrentTime())
+    session_end_time_ = runner_->GetCurrentTime();
+  local_state_.SetUserPref(prefs::kSessionLengthLimit,
+                           base::Value::CreateIntegerValue(
+                               session_length_limit));
+}
+
+void SessionLengthLimiterTest::ExpectStopSession() {
+  Mock::VerifyAndClearExpectations(delegate_);
+  EXPECT_CALL(*delegate_, StopSession())
+    .Times(1)
+    .WillOnce(Invoke(this, &SessionLengthLimiterTest::CheckStopSessionTime));
+}
 
+void SessionLengthLimiterTest::CheckStopSessionTime() {
+  EXPECT_EQ(session_end_time_, runner_->GetCurrentTime());
+}
+
+void SessionLengthLimiterTest::CreateSessionLengthLimiter(
+    bool browser_restarted) {
+  session_length_limiter_.reset(
+      new SessionLengthLimiter(delegate_, browser_restarted));
+}
 // Verifies that the session start time in local state is updated during login
 // if no session start time has been stored before.
 TEST_F(SessionLengthLimiterTest, StartWithSessionStartTimeUnset) {
@@ -206,7 +242,7 @@ TEST_F(SessionLengthLimiterTest, StartWithSessionStartTimeInvalid) {
 // if a session start time lying in the future has been stored before.
 TEST_F(SessionLengthLimiterTest, StartWithSessionStartTimeFuture) {
   SetSessionStartTimePref(
-      (now_ + base::TimeDelta::FromHours(2)).ToInternalValue());
+      (session_start_time_ + base::TimeDelta::FromHours(2)).ToInternalValue());
   CreateSessionLengthLimiter(false);
   VerifySessionStartTimePref();
 }
@@ -214,8 +250,8 @@ TEST_F(SessionLengthLimiterTest, StartWithSessionStartTimeFuture) {
 // Verifies that the session start time in local state is updated during login
 // if a valid session start time has been stored before.
 TEST_F(SessionLengthLimiterTest, StartWithSessionStartTimeValid) {
-  const base::Time previous_start_time = now_ - base::TimeDelta::FromHours(2);
-  SetSessionStartTimePref(previous_start_time.ToInternalValue());
+  SetSessionStartTimePref(
+      (session_start_time_ - base::TimeDelta::FromHours(2)).ToInternalValue());
   CreateSessionLengthLimiter(false);
   VerifySessionStartTimePref();
 }
@@ -240,7 +276,7 @@ TEST_F(SessionLengthLimiterTest, RestartWithSessionStartTimeInvalid) {
 // before.
 TEST_F(SessionLengthLimiterTest, RestartWithSessionStartTimeFuture) {
   SetSessionStartTimePref(
-      (now_ + base::TimeDelta::FromHours(2)).ToInternalValue());
+      (session_start_time_ + base::TimeDelta::FromHours(2)).ToInternalValue());
   CreateSessionLengthLimiter(true);
   VerifySessionStartTimePref();
 }
@@ -262,8 +298,8 @@ TEST_F(SessionLengthLimiterTest, RunWithoutSessionLengthLimit) {
   // Create a SessionLengthLimiter.
   CreateSessionLengthLimiter(false);
 
-  // Verify that no timer tick has been enqueued.
-  VerifyNoTimerTickIsEnqueued();
+  // Verify that no timer fires to terminate the session.
+  runner_->FastForwardUntilNoTasksRemain();
 }
 
 // Creates a SessionLengthLimiter after setting a limit. Verifies that the
@@ -278,13 +314,10 @@ TEST_F(SessionLengthLimiterTest, RunWithSessionLengthLimit) {
   // Create a SessionLengthLimiter.
   CreateSessionLengthLimiter(false);
 
-  // Check timer ticks until the remaining session time reaches zero.
-  while (*remaining_ > kZeroTimeDelta)
-    VerifyTimerTick();
-
-  // Check that the next timer tick leads to the session being terminated.
+  // Verify that the timer fires and the session is terminated when the session
+  // length limit is reached.
   ExpectStopSession();
-  VerifyTimerTick();
+  runner_->FastForwardUntilNoTasksRemain();
 }
 
 // Creates a SessionLengthLimiter after setting a 60 second limit, allows 50
@@ -300,20 +333,17 @@ TEST_F(SessionLengthLimiterTest, RunAndIncreaseSessionLengthLimit) {
   // Create a SessionLengthLimiter.
   CreateSessionLengthLimiter(false);
 
-  // Check timer ticks for 50 seconds of session time.
-  while (*remaining_ > kTenSeconds)
-    VerifyTimerTick();
+  // Fast forward the time by 50 seconds, verifying that no timer fires to
+  // terminate the session.
+  runner_->FastForwardBy(50 * 1000);  // 50 seconds.
 
   // Increase the session length limit to 90 seconds.
   SetSessionLengthLimitPref(90 * 1000);  // 90 seconds.
 
-  // Check timer ticks until the remaining session time reaches zero.
-  while (*remaining_  > kZeroTimeDelta)
-    VerifyTimerTick();
-
-  // Check that the next timer tick leads to the session being terminated.
+  // Verify that the the timer fires and the session is terminated when the
+  // session length limit is reached.
   ExpectStopSession();
-  VerifyTimerTick();
+  runner_->FastForwardUntilNoTasksRemain();
 }
 
 // Creates a SessionLengthLimiter after setting a 60 second limit, allows 50
@@ -330,17 +360,14 @@ TEST_F(SessionLengthLimiterTest, RunAndDecreaseSessionLengthLimit) {
   // Create a SessionLengthLimiter.
   CreateSessionLengthLimiter(false);
 
-  // Check timer ticks for 50 seconds of session time.
-  while (*remaining_ > kTenSeconds)
-    VerifyTimerTick();
-
-  // Reduce the session length limit below the 50 seconds that have already
-  // elapsed.
-  SetSessionLengthLimitPref(40 * 1000);  // 40 seconds.
+  // Fast forward the time by 50 seconds, verifying that no timer fires to
+  // terminate the session.
+  runner_->FastForwardBy(50 * 1000);  // 50 seconds.
 
-  // Check that the next timer tick causes the session to be terminated.
+  // Verify that reducing the session length limit below the 50 seconds that
+  // have already elapsed causes the session to be terminated immediately.
   ExpectStopSession();
-  VerifyTimerTick();
+  SetSessionLengthLimitPref(40 * 1000);  // 40 seconds.
 }
 
 // Creates a SessionLengthLimiter after setting a 60 second limit, allows 50
@@ -356,28 +383,15 @@ TEST_F(SessionLengthLimiterTest, RunAndRemoveSessionLengthLimit) {
   // Create a SessionLengthLimiter.
   CreateSessionLengthLimiter(false);
 
-  // Check timer ticks for 50 seconds of session time.
-  while (*remaining_ > kTenSeconds)
-    VerifyTimerTick();
+  // Fast forward the time by 50 seconds, verifying that no timer fires to
+  // terminate the session.
+  runner_->FastForwardBy(50 * 1000);  // 50 seconds.
 
   // Remove the session length limit.
   local_state_.RemoveUserPref(prefs::kSessionLengthLimit);
 
-  // Continue advancing the session time until it reaches the original 60 second
-  // limit.
-  while (*remaining_ > kZeroTimeDelta) {
-    runner_->RunTasks();
-
-    now_ += kSessionLengthLimitTimerInterval;
-    *remaining_ -= kSessionLengthLimitTimerInterval;
-    if (*remaining_ < kZeroTimeDelta)
-      remaining_.reset(new base::TimeDelta(kZeroTimeDelta));
-  }
-
-  // Check that the next timer tick does not lead to the session being
-  // terminated.
-  now_ += kSessionLengthLimitTimerInterval;
-  runner_->RunTasks();
+  // Verify that no timer fires to terminate the session.
+  runner_->FastForwardUntilNoTasksRemain();
 }
 
 }  // namespace chromeos