base/run_loop_unittest.cc

   1 // Copyright 2016 The Chromium Authors
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "base/run_loop.h"
   6
   7 #include <functional>
   8 #include <memory>
   9 #include <utility>
  10
  11 #include "base/bind.h"
  12 #include "base/callback_helpers.h"
  13 #include "base/containers/queue.h"
  14 #include "base/location.h"
  15 #include "base/memory/ptr_util.h"
  16 #include "base/memory/ref_counted.h"
  17 #include "base/synchronization/lock.h"
  18 #include "base/synchronization/waitable_event.h"
  19 #include "base/task/single_thread_task_runner.h"
  20 #include "base/test/bind.h"
  21 #include "base/test/gtest_util.h"
  22 #include "base/test/scoped_run_loop_timeout.h"
  23 #include "base/test/task_environment.h"
  24 #include "base/test/test_timeouts.h"
  25 #include "base/threading/platform_thread.h"
  26 #include "base/threading/sequenced_task_runner_handle.h"
  27 #include "base/threading/thread.h"
  28 #include "base/threading/thread_checker_impl.h"
  29 #include "base/threading/thread_task_runner_handle.h"
  30 #include "build/build_config.h"
  31 #include "testing/gmock/include/gmock/gmock.h"
  32 #include "testing/gtest/include/gtest/gtest.h"
  33
  34 namespace base {
  35
  36 namespace {
  37
  38 void QuitWhenIdleTask(RunLoop* run_loop, int* counter) {
  39   run_loop->QuitWhenIdle();
  40   ++(*counter);
  41 }
  42
  43 void RunNestedLoopTask(int* counter) {
  44   RunLoop nested_run_loop(RunLoop::Type::kNestableTasksAllowed);
  45
  46   // This task should quit |nested_run_loop| but not the main RunLoop.
  47   ThreadTaskRunnerHandle::Get()->PostTask(
  48       FROM_HERE, BindOnce(&QuitWhenIdleTask, Unretained(&nested_run_loop),
  49                           Unretained(counter)));
  50
  51   ThreadTaskRunnerHandle::Get()->PostDelayedTask(
  52       FROM_HERE, MakeExpectedNotRunClosure(FROM_HERE), Days(1));
  53
  54   nested_run_loop.Run();
  55
  56   ++(*counter);
  57 }
  58
  59 // A simple SingleThreadTaskRunner that just queues undelayed tasks (and ignores
  60 // delayed tasks). Tasks can then be processed one by one by ProcessTask() which
  61 // will return true if it processed a task and false otherwise.
  62 class SimpleSingleThreadTaskRunner : public SingleThreadTaskRunner {
  63  public:
  64   SimpleSingleThreadTaskRunner() = default;
  65   SimpleSingleThreadTaskRunner(const SimpleSingleThreadTaskRunner&) = delete;
  66   SimpleSingleThreadTaskRunner& operator=(const SimpleSingleThreadTaskRunner&) =
  67       delete;
  68
  69   bool PostDelayedTask(const Location& from_here,
  70                        OnceClosure task,
  71                        base::TimeDelta delay) override {
  72     if (delay.is_positive())
  73       return false;
  74     AutoLock auto_lock(tasks_lock_);
  75     pending_tasks_.push(std::move(task));
  76     return true;
  77   }
  78
  79   bool PostNonNestableDelayedTask(const Location& from_here,
  80                                   OnceClosure task,
  81                                   base::TimeDelta delay) override {
  82     return PostDelayedTask(from_here, std::move(task), delay);
  83   }
  84
  85   bool RunsTasksInCurrentSequence() const override {
  86     return origin_thread_checker_.CalledOnValidThread();
  87   }
  88
  89   bool ProcessSingleTask() {
  90     OnceClosure task;
  91     {
  92       AutoLock auto_lock(tasks_lock_);
  93       if (pending_tasks_.empty())
  94         return false;
  95       task = std::move(pending_tasks_.front());
  96       pending_tasks_.pop();
  97     }
  98     // It's important to Run() after pop() and outside the lock as |task| may
  99     // run a nested loop which will re-enter ProcessSingleTask().
 100     std::move(task).Run();
 101     return true;
 102   }
 103
 104  private:
 105   ~SimpleSingleThreadTaskRunner() override = default;
 106
 107   Lock tasks_lock_;
 108   base::queue<OnceClosure> pending_tasks_;
 109
 110   // RunLoop relies on RunsTasksInCurrentSequence() signal. Use a
 111   // ThreadCheckerImpl to be able to reliably provide that signal even in
 112   // non-dcheck builds.
 113   ThreadCheckerImpl origin_thread_checker_;
 114 };
 115
 116 // The basis of all TestDelegates, allows safely injecting a OnceClosure to be
 117 // run in the next idle phase of this delegate's Run() implementation. This can
 118 // be used to have code run on a thread that is otherwise livelocked in an idle
 119 // phase (sometimes a simple PostTask() won't do it -- e.g. when processing
 120 // application tasks is disallowed).
 121 class InjectableTestDelegate : public RunLoop::Delegate {
 122  public:
 123   void InjectClosureOnDelegate(OnceClosure closure) {
 124     AutoLock auto_lock(closure_lock_);
 125     closure_ = std::move(closure);
 126   }
 127
 128   bool RunInjectedClosure() {
 129     AutoLock auto_lock(closure_lock_);
 130     if (closure_.is_null())
 131       return false;
 132     std::move(closure_).Run();
 133     return true;
 134   }
 135
 136  private:
 137   Lock closure_lock_;
 138   OnceClosure closure_;
 139 };
 140
 141 // A simple test RunLoop::Delegate to exercise Runloop logic independent of any
 142 // other base constructs. BindToCurrentThread() must be called before this
 143 // TestBoundDelegate is operational.
 144 class TestBoundDelegate final : public InjectableTestDelegate {
 145  public:
 146   TestBoundDelegate() = default;
 147
 148   // Makes this TestBoundDelegate become the RunLoop::Delegate and
 149   // ThreadTaskRunnerHandle for this thread.
 150   void BindToCurrentThread() {
 151     thread_task_runner_handle_ =
 152         std::make_unique<ThreadTaskRunnerHandle>(simple_task_runner_);
 153     RunLoop::RegisterDelegateForCurrentThread(this);
 154   }
 155
 156  private:
 157   void Run(bool application_tasks_allowed, TimeDelta timeout) override {
 158     if (nested_run_allowing_tasks_incoming_) {
 159       EXPECT_TRUE(RunLoop::IsNestedOnCurrentThread());
 160       EXPECT_TRUE(application_tasks_allowed);
 161     } else if (RunLoop::IsNestedOnCurrentThread()) {
 162       EXPECT_FALSE(application_tasks_allowed);
 163     }
 164     nested_run_allowing_tasks_incoming_ = false;
 165
 166     while (!should_quit_) {
 167       if (application_tasks_allowed && simple_task_runner_->ProcessSingleTask())
 168         continue;
 169
 170       if (ShouldQuitWhenIdle())
 171         break;
 172
 173       if (RunInjectedClosure())
 174         continue;
 175
 176       PlatformThread::YieldCurrentThread();
 177     }
 178     should_quit_ = false;
 179   }
 180
 181   void Quit() override { should_quit_ = true; }
 182
 183   void EnsureWorkScheduled() override {
 184     nested_run_allowing_tasks_incoming_ = true;
 185   }
 186
 187   // True if the next invocation of Run() is expected to be from a
 188   // kNestableTasksAllowed RunLoop.
 189   bool nested_run_allowing_tasks_incoming_ = false;
 190
 191   scoped_refptr<SimpleSingleThreadTaskRunner> simple_task_runner_ =
 192       MakeRefCounted<SimpleSingleThreadTaskRunner>();
 193
 194   std::unique_ptr<ThreadTaskRunnerHandle> thread_task_runner_handle_;
 195
 196   bool should_quit_ = false;
 197 };
 198
 199 enum class RunLoopTestType {
 200   // Runs all RunLoopTests under a TaskEnvironment to make sure real world
 201   // scenarios work.
 202   kRealEnvironment,
 203
 204   // Runs all RunLoopTests under a test RunLoop::Delegate to make sure the
 205   // delegate interface fully works standalone.
 206   kTestDelegate,
 207 };
 208
 209 // The task environment for the RunLoopTest of a given type. A separate class
 210 // so it can be instantiated on the stack in the RunLoopTest fixture.
 211 class RunLoopTestEnvironment {
 212  public:
 213   explicit RunLoopTestEnvironment(RunLoopTestType type) {
 214     switch (type) {
 215       case RunLoopTestType::kRealEnvironment: {
 216         task_environment_ = std::make_unique<test::TaskEnvironment>();
 217         break;
 218       }
 219       case RunLoopTestType::kTestDelegate: {
 220         auto test_delegate = std::make_unique<TestBoundDelegate>();
 221         test_delegate->BindToCurrentThread();
 222         test_delegate_ = std::move(test_delegate);
 223         break;
 224       }
 225     }
 226   }
 227
 228  private:
 229   // Instantiates one or the other based on the RunLoopTestType.
 230   std::unique_ptr<test::TaskEnvironment> task_environment_;
 231   std::unique_ptr<InjectableTestDelegate> test_delegate_;
 232 };
 233
 234 class RunLoopTest : public testing::TestWithParam<RunLoopTestType> {
 235  public:
 236   RunLoopTest(const RunLoopTest&) = delete;
 237   RunLoopTest& operator=(const RunLoopTest&) = delete;
 238
 239  protected:
 240   RunLoopTest() : test_environment_(GetParam()) {}
 241
 242   RunLoopTestEnvironment test_environment_;
 243   RunLoop run_loop_;
 244 };
 245
 246 }  // namespace
 247
 248 TEST_P(RunLoopTest, QuitWhenIdle) {
 249   int counter = 0;
 250   ThreadTaskRunnerHandle::Get()->PostTask(
 251       FROM_HERE, BindOnce(&QuitWhenIdleTask, Unretained(&run_loop_),
 252                           Unretained(&counter)));
 253   ThreadTaskRunnerHandle::Get()->PostTask(FROM_HERE,
 254                                           MakeExpectedRunClosure(FROM_HERE));
 255   ThreadTaskRunnerHandle::Get()->PostDelayedTask(
 256       FROM_HERE, MakeExpectedNotRunClosure(FROM_HERE), Days(1));
 257
 258   run_loop_.Run();
 259   EXPECT_EQ(1, counter);
 260 }
 261
 262 TEST_P(RunLoopTest, QuitWhenIdleNestedLoop) {
 263   int counter = 0;
 264   ThreadTaskRunnerHandle::Get()->PostTask(
 265       FROM_HERE, BindOnce(&RunNestedLoopTask, Unretained(&counter)));
 266   ThreadTaskRunnerHandle::Get()->PostTask(
 267       FROM_HERE, BindOnce(&QuitWhenIdleTask, Unretained(&run_loop_),
 268                           Unretained(&counter)));
 269   ThreadTaskRunnerHandle::Get()->PostTask(FROM_HERE,
 270                                           MakeExpectedRunClosure(FROM_HERE));
 271   ThreadTaskRunnerHandle::Get()->PostDelayedTask(
 272       FROM_HERE, MakeExpectedNotRunClosure(FROM_HERE), Days(1));
 273
 274   run_loop_.Run();
 275   EXPECT_EQ(3, counter);
 276 }
 277
 278 TEST_P(RunLoopTest, QuitWhenIdleClosure) {
 279   ThreadTaskRunnerHandle::Get()->PostTask(FROM_HERE,
 280                                           run_loop_.QuitWhenIdleClosure());
 281   ThreadTaskRunnerHandle::Get()->PostTask(FROM_HERE,
 282                                           MakeExpectedRunClosure(FROM_HERE));
 283   ThreadTaskRunnerHandle::Get()->PostDelayedTask(
 284       FROM_HERE, MakeExpectedNotRunClosure(FROM_HERE), Days(1));
 285
 286   run_loop_.Run();
 287 }
 288
 289 // Verify that the QuitWhenIdleClosure() can run after the RunLoop has been
 290 // deleted. It should have no effect.
 291 TEST_P(RunLoopTest, QuitWhenIdleClosureAfterRunLoopScope) {
 292   RepeatingClosure quit_when_idle_closure;
 293   {
 294     RunLoop run_loop;
 295     quit_when_idle_closure = run_loop.QuitWhenIdleClosure();
 296     run_loop.RunUntilIdle();
 297   }
 298   quit_when_idle_closure.Run();
 299 }
 300
 301 // Verify that Quit can be executed from another sequence.
 302 TEST_P(RunLoopTest, QuitFromOtherSequence) {
 303   Thread other_thread("test");
 304   other_thread.Start();
 305   scoped_refptr<SequencedTaskRunner> other_sequence =
 306       other_thread.task_runner();
 307
 308   // Always expected to run before asynchronous Quit() kicks in.
 309   ThreadTaskRunnerHandle::Get()->PostTask(FROM_HERE,
 310                                           MakeExpectedRunClosure(FROM_HERE));
 311
 312   WaitableEvent loop_was_quit(WaitableEvent::ResetPolicy::MANUAL,
 313                               WaitableEvent::InitialState::NOT_SIGNALED);
 314   other_sequence->PostTask(
 315       FROM_HERE, base::BindOnce([](RunLoop* run_loop) { run_loop->Quit(); },
 316                                 Unretained(&run_loop_)));
 317   other_sequence->PostTask(
 318       FROM_HERE,
 319       base::BindOnce(&WaitableEvent::Signal, base::Unretained(&loop_was_quit)));
 320
 321   // Anything that's posted after the Quit closure was posted back to this
 322   // sequence shouldn't get a chance to run.
 323   loop_was_quit.Wait();
 324   ThreadTaskRunnerHandle::Get()->PostTask(FROM_HERE,
 325                                           MakeExpectedNotRunClosure(FROM_HERE));
 326
 327   run_loop_.Run();
 328 }
 329
 330 // Verify that QuitClosure can be executed from another sequence.
 331 TEST_P(RunLoopTest, QuitFromOtherSequenceWithClosure) {
 332   Thread other_thread("test");
 333   other_thread.Start();
 334   scoped_refptr<SequencedTaskRunner> other_sequence =
 335       other_thread.task_runner();
 336
 337   // Always expected to run before asynchronous Quit() kicks in.
 338   ThreadTaskRunnerHandle::Get()->PostTask(FROM_HERE,
 339                                           MakeExpectedRunClosure(FROM_HERE));
 340
 341   WaitableEvent loop_was_quit(WaitableEvent::ResetPolicy::MANUAL,
 342                               WaitableEvent::InitialState::NOT_SIGNALED);
 343   other_sequence->PostTask(FROM_HERE, run_loop_.QuitClosure());
 344   other_sequence->PostTask(
 345       FROM_HERE,
 346       base::BindOnce(&WaitableEvent::Signal, base::Unretained(&loop_was_quit)));
 347
 348   // Anything that's posted after the Quit closure was posted back to this
 349   // sequence shouldn't get a chance to run.
 350   loop_was_quit.Wait();
 351   ThreadTaskRunnerHandle::Get()->PostTask(FROM_HERE,
 352                                           MakeExpectedNotRunClosure(FROM_HERE));
 353
 354   run_loop_.Run();
 355 }
 356
 357 // Verify that Quit can be executed from another sequence even when the
 358 // Quit is racing with Run() -- i.e. forgo the WaitableEvent used above.
 359 TEST_P(RunLoopTest, QuitFromOtherSequenceRacy) {
 360   Thread other_thread("test");
 361   other_thread.Start();
 362   scoped_refptr<SequencedTaskRunner> other_sequence =
 363       other_thread.task_runner();
 364
 365   // Always expected to run before asynchronous Quit() kicks in.
 366   ThreadTaskRunnerHandle::Get()->PostTask(FROM_HERE,
 367                                           MakeExpectedRunClosure(FROM_HERE));
 368
 369   other_sequence->PostTask(FROM_HERE, run_loop_.QuitClosure());
 370
 371   run_loop_.Run();
 372 }
 373
 374 // Verify that QuitClosure can be executed from another sequence even when the
 375 // Quit is racing with Run() -- i.e. forgo the WaitableEvent used above.
 376 TEST_P(RunLoopTest, QuitFromOtherSequenceRacyWithClosure) {
 377   Thread other_thread("test");
 378   other_thread.Start();
 379   scoped_refptr<SequencedTaskRunner> other_sequence =
 380       other_thread.task_runner();
 381
 382   // Always expected to run before asynchronous Quit() kicks in.
 383   ThreadTaskRunnerHandle::Get()->PostTask(FROM_HERE,
 384                                           MakeExpectedRunClosure(FROM_HERE));
 385
 386   other_sequence->PostTask(FROM_HERE, run_loop_.QuitClosure());
 387
 388   run_loop_.Run();
 389 }
 390
 391 // Verify that QuitWhenIdle can be executed from another sequence.
 392 TEST_P(RunLoopTest, QuitWhenIdleFromOtherSequence) {
 393   Thread other_thread("test");
 394   other_thread.Start();
 395   scoped_refptr<SequencedTaskRunner> other_sequence =
 396       other_thread.task_runner();
 397
 398   ThreadTaskRunnerHandle::Get()->PostTask(FROM_HERE,
 399                                           MakeExpectedRunClosure(FROM_HERE));
 400
 401   other_sequence->PostTask(
 402       FROM_HERE,
 403       base::BindOnce([](RunLoop* run_loop) { run_loop->QuitWhenIdle(); },
 404                      Unretained(&run_loop_)));
 405
 406   ThreadTaskRunnerHandle::Get()->PostTask(FROM_HERE,
 407                                           MakeExpectedRunClosure(FROM_HERE));
 408
 409   run_loop_.Run();
 410
 411   // Regardless of the outcome of the race this thread shouldn't have been idle
 412   // until both tasks posted to this sequence have run.
 413 }
 414
 415 // Verify that QuitWhenIdleClosure can be executed from another sequence.
 416 TEST_P(RunLoopTest, QuitWhenIdleFromOtherSequenceWithClosure) {
 417   Thread other_thread("test");
 418   other_thread.Start();
 419   scoped_refptr<SequencedTaskRunner> other_sequence =
 420       other_thread.task_runner();
 421
 422   ThreadTaskRunnerHandle::Get()->PostTask(FROM_HERE,
 423                                           MakeExpectedRunClosure(FROM_HERE));
 424
 425   other_sequence->PostTask(FROM_HERE, run_loop_.QuitWhenIdleClosure());
 426
 427   ThreadTaskRunnerHandle::Get()->PostTask(FROM_HERE,
 428                                           MakeExpectedRunClosure(FROM_HERE));
 429
 430   run_loop_.Run();
 431
 432   // Regardless of the outcome of the race this thread shouldn't have been idle
 433   // until the both tasks posted to this sequence have run.
 434 }
 435
 436 TEST_P(RunLoopTest, IsRunningOnCurrentThread) {
 437   EXPECT_FALSE(RunLoop::IsRunningOnCurrentThread());
 438   ThreadTaskRunnerHandle::Get()->PostTask(
 439       FROM_HERE,
 440       BindOnce([]() { EXPECT_TRUE(RunLoop::IsRunningOnCurrentThread()); }));
 441   ThreadTaskRunnerHandle::Get()->PostTask(FROM_HERE, run_loop_.QuitClosure());
 442   run_loop_.Run();
 443 }
 444
 445 TEST_P(RunLoopTest, IsNestedOnCurrentThread) {
 446   EXPECT_FALSE(RunLoop::IsNestedOnCurrentThread());
 447
 448   ThreadTaskRunnerHandle::Get()->PostTask(
 449       FROM_HERE, BindOnce([]() {
 450         EXPECT_FALSE(RunLoop::IsNestedOnCurrentThread());
 451
 452         RunLoop nested_run_loop(RunLoop::Type::kNestableTasksAllowed);
 453
 454         ThreadTaskRunnerHandle::Get()->PostTask(
 455             FROM_HERE, BindOnce([]() {
 456               EXPECT_TRUE(RunLoop::IsNestedOnCurrentThread());
 457             }));
 458         ThreadTaskRunnerHandle::Get()->PostTask(FROM_HERE,
 459                                                 nested_run_loop.QuitClosure());
 460
 461         EXPECT_FALSE(RunLoop::IsNestedOnCurrentThread());
 462         nested_run_loop.Run();
 463         EXPECT_FALSE(RunLoop::IsNestedOnCurrentThread());
 464       }));
 465
 466   ThreadTaskRunnerHandle::Get()->PostTask(FROM_HERE, run_loop_.QuitClosure());
 467   run_loop_.Run();
 468 }
 469
 470 TEST_P(RunLoopTest, CannotRunMoreThanOnce) {
 471   ThreadTaskRunnerHandle::Get()->PostTask(FROM_HERE, run_loop_.QuitClosure());
 472   run_loop_.Run();
 473   EXPECT_DCHECK_DEATH({ run_loop_.Run(); });
 474 }
 475
 476 TEST_P(RunLoopTest, CanRunUntilIdleMoreThanOnce) {
 477   ThreadTaskRunnerHandle::Get()->PostTask(FROM_HERE, DoNothing());
 478   run_loop_.RunUntilIdle();
 479
 480   ThreadTaskRunnerHandle::Get()->PostTask(FROM_HERE, DoNothing());
 481   run_loop_.RunUntilIdle();
 482   run_loop_.RunUntilIdle();
 483 }
 484
 485 TEST_P(RunLoopTest, CanRunUntilIdleThenRunIfNotQuit) {
 486   ThreadTaskRunnerHandle::Get()->PostTask(FROM_HERE, DoNothing());
 487   run_loop_.RunUntilIdle();
 488
 489   ThreadTaskRunnerHandle::Get()->PostTask(FROM_HERE, run_loop_.QuitClosure());
 490   run_loop_.Run();
 491 }
 492
 493 TEST_P(RunLoopTest, CannotRunUntilIdleThenRunIfQuit) {
 494   ThreadTaskRunnerHandle::Get()->PostTask(FROM_HERE, run_loop_.QuitClosure());
 495   run_loop_.RunUntilIdle();
 496
 497   ThreadTaskRunnerHandle::Get()->PostTask(FROM_HERE, DoNothing());
 498   EXPECT_DCHECK_DEATH({ run_loop_.Run(); });
 499 }
 500
 501 TEST_P(RunLoopTest, CannotRunAgainIfQuitWhenIdle) {
 502   ThreadTaskRunnerHandle::Get()->PostTask(FROM_HERE,
 503                                           run_loop_.QuitWhenIdleClosure());
 504   run_loop_.RunUntilIdle();
 505
 506   EXPECT_DCHECK_DEATH({ run_loop_.RunUntilIdle(); });
 507 }
 508
 509 namespace {
 510
 511 class MockNestingObserver : public RunLoop::NestingObserver {
 512  public:
 513   MockNestingObserver() = default;
 514   MockNestingObserver(const MockNestingObserver&) = delete;
 515   MockNestingObserver& operator=(const MockNestingObserver&) = delete;
 516
 517   // RunLoop::NestingObserver:
 518   MOCK_METHOD0(OnBeginNestedRunLoop, void());
 519   MOCK_METHOD0(OnExitNestedRunLoop, void());
 520 };
 521
 522 class MockTask {
 523  public:
 524   MockTask() = default;
 525   MockTask(const MockTask&) = delete;
 526   MockTask& operator=(const MockTask&) = delete;
 527
 528   MOCK_METHOD0(Task, void());
 529 };
 530
 531 }  // namespace
 532
 533 TEST_P(RunLoopTest, NestingObservers) {
 534   testing::StrictMock<MockNestingObserver> nesting_observer;
 535   testing::StrictMock<MockTask> mock_task_a;
 536   testing::StrictMock<MockTask> mock_task_b;
 537
 538   RunLoop::AddNestingObserverOnCurrentThread(&nesting_observer);
 539
 540   const RepeatingClosure run_nested_loop = BindRepeating([]() {
 541     RunLoop nested_run_loop(RunLoop::Type::kNestableTasksAllowed);
 542     ThreadTaskRunnerHandle::Get()->PostTask(FROM_HERE,
 543                                             nested_run_loop.QuitClosure());
 544     nested_run_loop.Run();
 545   });
 546
 547   // Generate a stack of nested RunLoops. OnBeginNestedRunLoop() is expected
 548   // when beginning each nesting depth and OnExitNestedRunLoop() is expected
 549   // when exiting each nesting depth. Each one of these tasks is ahead of the
 550   // QuitClosures as those are only posted at the end of the queue when
 551   // |run_nested_loop| is executed.
 552   ThreadTaskRunnerHandle::Get()->PostTask(FROM_HERE, run_nested_loop);
 553   ThreadTaskRunnerHandle::Get()->PostTask(
 554       FROM_HERE,
 555       base::BindOnce(&MockTask::Task, base::Unretained(&mock_task_a)));
 556   ThreadTaskRunnerHandle::Get()->PostTask(FROM_HERE, run_nested_loop);
 557   ThreadTaskRunnerHandle::Get()->PostTask(
 558       FROM_HERE,
 559       base::BindOnce(&MockTask::Task, base::Unretained(&mock_task_b)));
 560
 561   {
 562     testing::InSequence in_sequence;
 563     EXPECT_CALL(nesting_observer, OnBeginNestedRunLoop());
 564     EXPECT_CALL(mock_task_a, Task());
 565     EXPECT_CALL(nesting_observer, OnBeginNestedRunLoop());
 566     EXPECT_CALL(mock_task_b, Task());
 567     EXPECT_CALL(nesting_observer, OnExitNestedRunLoop()).Times(2);
 568   }
 569   run_loop_.RunUntilIdle();
 570
 571   RunLoop::RemoveNestingObserverOnCurrentThread(&nesting_observer);
 572 }
 573
 574 TEST_P(RunLoopTest, DisallowRunning) {
 575   ScopedDisallowRunningRunLoop disallow_running;
 576   EXPECT_DCHECK_DEATH({ run_loop_.RunUntilIdle(); });
 577 }
 578
 579 TEST_P(RunLoopTest, ExpiredDisallowRunning) {
 580   { ScopedDisallowRunningRunLoop disallow_running; }
 581   // Running should be fine after |disallow_running| goes out of scope.
 582   run_loop_.RunUntilIdle();
 583 }
 584
 585 INSTANTIATE_TEST_SUITE_P(Real,
 586                          RunLoopTest,
 587                          testing::Values(RunLoopTestType::kRealEnvironment));
 588 INSTANTIATE_TEST_SUITE_P(Mock,
 589                          RunLoopTest,
 590                          testing::Values(RunLoopTestType::kTestDelegate));
 591
 592 TEST(RunLoopDeathTest, MustRegisterBeforeInstantiating) {
 593   TestBoundDelegate unbound_test_delegate_;
 594   // RunLoop::RunLoop() should CHECK fetching the ThreadTaskRunnerHandle.
 595   EXPECT_DEATH_IF_SUPPORTED({ RunLoop(); }, "");
 596 }
 597
 598 TEST(RunLoopDelegateTest, NestableTasksDontRunInDefaultNestedLoops) {
 599   TestBoundDelegate test_delegate;
 600   test_delegate.BindToCurrentThread();
 601
 602   base::Thread other_thread("test");
 603   other_thread.Start();
 604
 605   RunLoop main_loop;
 606   // A nested run loop which isn't kNestableTasksAllowed.
 607   RunLoop nested_run_loop(RunLoop::Type::kDefault);
 608
 609   bool nested_run_loop_ended = false;
 610
 611   // The first task on the main loop will result in a nested run loop. Since
 612   // it's not kNestableTasksAllowed, no further task should be processed until
 613   // it's quit.
 614   ThreadTaskRunnerHandle::Get()->PostTask(
 615       FROM_HERE,
 616       BindOnce([](RunLoop* nested_run_loop) { nested_run_loop->Run(); },
 617                Unretained(&nested_run_loop)));
 618
 619   // Post a task that will fail if it runs inside the nested run loop.
 620   ThreadTaskRunnerHandle::Get()->PostTask(
 621       FROM_HERE,
 622       BindOnce(
 623           [](const bool& nested_run_loop_ended,
 624              OnceClosure continuation_callback) {
 625             EXPECT_TRUE(nested_run_loop_ended);
 626             EXPECT_FALSE(RunLoop::IsNestedOnCurrentThread());
 627             std::move(continuation_callback).Run();
 628           },
 629           std::cref(nested_run_loop_ended), main_loop.QuitClosure()));
 630
 631   // Post a task flipping the boolean bit for extra verification right before
 632   // quitting |nested_run_loop|.
 633   other_thread.task_runner()->PostDelayedTask(
 634       FROM_HERE,
 635       BindOnce(
 636           [](bool* nested_run_loop_ended) {
 637             EXPECT_FALSE(*nested_run_loop_ended);
 638             *nested_run_loop_ended = true;
 639           },
 640           Unretained(&nested_run_loop_ended)),
 641       TestTimeouts::tiny_timeout());
 642   // Post an async delayed task to exit the run loop when idle. This confirms
 643   // that (1) the test task only ran in the main loop after the nested loop
 644   // exited and (2) the nested run loop actually considers itself idle while
 645   // spinning. Note: The quit closure needs to be injected directly on the
 646   // delegate as invoking QuitWhenIdle() off-thread results in a thread bounce
 647   // which will not processed because of the very logic under test (nestable
 648   // tasks don't run in |nested_run_loop|).
 649   other_thread.task_runner()->PostDelayedTask(
 650       FROM_HERE,
 651       BindOnce(
 652           [](TestBoundDelegate* test_delegate, OnceClosure injected_closure) {
 653             test_delegate->InjectClosureOnDelegate(std::move(injected_closure));
 654           },
 655           Unretained(&test_delegate), nested_run_loop.QuitWhenIdleClosure()),
 656       TestTimeouts::tiny_timeout());
 657
 658   main_loop.Run();
 659 }
 660
 661 }  // namespace base