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// Copyright 2017 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.
#ifndef BASE_TEST_SCOPED_TASK_ENVIRONMENT_H_
#define BASE_TEST_SCOPED_TASK_ENVIRONMENT_H_
#include "base/macros.h"
#include "base/message_loop/message_loop.h"
namespace base {
class TaskScheduler;
namespace test {
// ScopedTaskEnvironment allows usage of these APIs within its scope:
// - (Thread|Sequenced)TaskRunnerHandle, on the thread where it lives
// - base/task_scheduler/post_task.h, on any thread
//
// Tests that need either of these APIs should instantiate a
// ScopedTaskEnvironment.
//
// Tasks posted to the (Thread|Sequenced)TaskRunnerHandle run synchronously when
// RunLoop::Run(UntilIdle) is called on the thread where the
// ScopedTaskEnvironment lives.
//
// Tasks posted through base/task_scheduler/post_task.h run on dedicated threads
// as they are posted.
//
// Usage:
//
// class MyTestFixture : public testing::Test {
// public:
// (...)
//
// protected:
// // Must be the first member (or at least before any member that cares
// // about tasks) to be initialized first and destroyed last. protected
// // instead of private visibility will allow controlling the task
// // environment (e.g. clock) once such features are added (see design doc
// // below for details), until then it at least doesn't hurt :).
// base::test::ScopedTaskEnvironment scoped_task_environment_;
//
// // Other members go here (or further below in private section.)
// };
//
// Design and future improvements documented in
// https://docs.google.com/document/d/1QabRo8c7D9LsYY3cEcaPQbOCLo8Tu-6VLykYXyl3Pkk/edit
class ScopedTaskEnvironment {
public:
enum class MainThreadType {
// The main thread doesn't pump system messages.
DEFAULT,
// The main thread pumps UI messages.
UI,
// The main thread pumps asynchronous IO messages.
IO,
};
ScopedTaskEnvironment(
MainThreadType main_thread_type = MainThreadType::DEFAULT);
// Runs pending (Thread|Sequenced)TaskRunnerHandle tasks and pending
// BLOCK_SHUTDOWN TaskScheduler tasks. Then, unregisters the TaskScheduler and
// the (Thread|Sequenced)TaskRunnerHandle.
~ScopedTaskEnvironment();
private:
// Note: |message_loop_| is an implementation detail and will be replaced in
// the future, do NOT rely on the presence of a MessageLoop beyond
// (Thread|Sequenced)TaskRunnerHandle and RunLoop.
MessageLoop message_loop_;
const TaskScheduler* task_scheduler_ = nullptr;
DISALLOW_COPY_AND_ASSIGN(ScopedTaskEnvironment);
};
} // namespace test
} // namespace base
#endif // BASE_TEST_SCOPED_ASYNC_TASK_SCHEDULER_H_