base: Make it possible to replace the MessageLoop's task runner

base/message_loop/message_loop_unittest.cc

Index: base/message_loop/message_loop_unittest.cc
diff --git a/base/message_loop/message_loop_unittest.cc b/base/message_loop/message_loop_unittest.cc
index 48c82c4792b51a5e0d67e9ca7737bd24a885e4bb..7c78d37bf02e0a91bf103e4558e6c79ee9f987b2 100644
--- a/base/message_loop/message_loop_unittest.cc
+++ b/base/message_loop/message_loop_unittest.cc
@@ -9,12 +9,14 @@
 #include "base/compiler_specific.h"
 #include "base/logging.h"
 #include "base/memory/ref_counted.h"
+#include "base/message_loop/bindable_single_thread_task_runner.h"
 #include "base/message_loop/message_loop.h"
 #include "base/message_loop/message_loop_test.h"
 #include "base/pending_task.h"
 #include "base/posix/eintr_wrapper.h"
 #include "base/run_loop.h"
 #include "base/synchronization/waitable_event.h"
+#include "base/test/test_simple_task_runner.h"
 #include "base/thread_task_runner_handle.h"
 #include "base/threading/platform_thread.h"
 #include "base/threading/thread.h"
@@ -1011,4 +1013,68 @@ TEST(MessageLoopTest, AlwaysHaveUserMessageWhenNesting) {
 }
 #endif  // defined(OS_WIN)
 
+class TestTaskRunner : public BindableSingleThreadTaskRunner {
+ public:
+  TestTaskRunner() : was_bound_(false) {}
+
+  // BindableSingleThreadTaskRunner implementation:
+  void BindToCurrentThread() override { was_bound_ = true; }
+  bool PostDelayedTask(const tracked_objects::Location& from_here,
+                       const base::Closure& task,
+                       base::TimeDelta delay) override {
+    return false;
+  }
+  bool PostNonNestableDelayedTask(const tracked_objects::Location& from_here,
+                                  const base::Closure& task,
+                                  base::TimeDelta delay) override {
+    return false;
+  }
+  bool RunsTasksOnCurrentThread() const override { return was_bound_; }
+
+  bool was_bound() const { return was_bound_; }
+
+ private:
+  ~TestTaskRunner() override {}
+
+  bool was_bound_;
+};
+
+TEST(MessageLoopTest, SwapTaskRunnerBeforeBinding) {
+  scoped_ptr<MessageLoop> loop(MessageLoop::CreateUnbound(
+      MessageLoop::TYPE_DEFAULT, MessageLoop::MessagePumpFactoryCallback()));
+  scoped_refptr<TestTaskRunner> new_runner(new TestTaskRunner());
+
+  loop->SwapTaskRunner(new_runner);
+  EXPECT_EQ(new_runner, loop->task_runner());
+
+  loop->BindToCurrentThread();
+  EXPECT_TRUE(new_runner->was_bound());
+  EXPECT_EQ(new_runner, ThreadTaskRunnerHandle::Get());
+}
+
+TEST(MessageLoopTest, SwapTaskRunnerAfterBinding) {
+  MessageLoop loop;
+  scoped_refptr<TestTaskRunner> new_runner(new TestTaskRunner());
+
+  new_runner->BindToCurrentThread();
+  loop.SwapTaskRunner(new_runner);
+  EXPECT_EQ(new_runner, loop.task_runner());
+  EXPECT_EQ(new_runner, ThreadTaskRunnerHandle::Get());
+}
+
+TEST(MessageLoopTest, OriginalRunnerWorks) {
+  MessageLoop loop;
+  scoped_refptr<TestTaskRunner> new_runner(new TestTaskRunner());
+
+  new_runner->BindToCurrentThread();
+  scoped_refptr<BindableSingleThreadTaskRunner> original_runner(
+      loop.SwapTaskRunner(new_runner));
+
+  scoped_refptr<Foo> foo(new Foo());
+  original_runner->PostTask(FROM_HERE,
+                            Bind(&Foo::Test1ConstRef, foo.get(), "a"));
+  loop.RunUntilIdle();
+  EXPECT_EQ(1, foo->test_count());
+}
+
 }  // namespace base