Create LibDispatchTaskRunner, a SingleThreadTaskRunner that is backed by a libdispatch queue.

base/mac/libdispatch_task_runner_unittest.cc

+// Copyright (c) 2012 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 "base/mac/libdispatch_task_runner.h"
+
+#include "base/bind.h"
+#include "base/mac/bind_objc_block.h"
+#include "base/message_loop.h"
+#include "base/stringprintf.h"
+#include "base/synchronization/lock.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+class LibDispatchTaskRunnerTest : public testing::Test {
+ public:
+  virtual void SetUp() OVERRIDE {
+    task_runner_ = new base::mac::LibDispatchTaskRunner(
+        "org.chromium.LibDispatchTaskRunnerTest");
+  }
+
+  // DispatchLastTask is used to run the main test thread's MessageLoop until
+  // all non-delayed tasks are run on the LibDispatchTaskRunner.
+  void DispatchLastTask() {
+    dispatch_async(task_runner_->GetDispatchQueue(), ^{
+        (&message_loop_)->PostTask(FROM_HERE, MessageLoop::QuitClosure());
+    });
+    message_loop_.Run();
+  }
+
+  // VerifyTaskOrder takes the expectations from TaskOrderMarkers and compares
+  // them against the recorded values.
+  void VerifyTaskOrder(const char* expectations[], size_t num_expectations) {

[Mark Mentovai, 2012/12/06 22:11:45]

I would make this conster, because I’d want the actual expectations later in the
file to be conster too. You will get better code that way.

[Robert Sesek, 2012/12/06 22:18:05]

Done.

+    size_t actual_size = task_order_.size();
+
+    for (size_t i = 0; i < num_expectations; ++i) {
+      if (i >= actual_size) {
+        EXPECT_LT(i, actual_size) << "Expected " << expectations[i];
+        continue;
+      }
+
+      EXPECT_EQ(expectations[i], task_order_[i]);
+    }
+
+    if (actual_size > num_expectations) {
+      EXPECT_LE(actual_size, num_expectations) << "Extra tasks were run:";
+      for (size_t i = num_expectations; i < actual_size; ++i) {
+        EXPECT_EQ("<none>", task_order_[i]) << " (i=" << i << ")";
+      }
+    }
+  }
+
+  // The message loop for the test main thread.
+  MessageLoop message_loop_;
+
+  // The task runner under test.
+  scoped_refptr<base::mac::LibDispatchTaskRunner> task_runner_;
+
+  // Vector that records data from TaskOrderMarker.
+  std::vector<std::string> task_order_;
+};
+
+// Scoper that records the beginning and end of a running task.
+class TaskOrderMarker {
+ public:
+  TaskOrderMarker(LibDispatchTaskRunnerTest* test, const std::string& name)
+      : test_(test),
+        name_(name) {
+    test->task_order_.push_back(std::string("BEGIN ") + name);
+  }
+  ~TaskOrderMarker() {
+    test_->task_order_.push_back(std::string("END ") + name_);
+  }
+
+ private:
+  LibDispatchTaskRunnerTest* test_;
+  std::string name_;
+};
+
+void RecordTaskOrder(LibDispatchTaskRunnerTest* test, const std::string& name) {
+  TaskOrderMarker marker(test, name);
+}
+
+// Returns a closure that records the task order.
+base::Closure BoundRecordTaskOrder(LibDispatchTaskRunnerTest* test,
+                                   const std::string& name) {
+  return base::Bind(&RecordTaskOrder, base::Unretained(test), name);
+}
+
+TEST_F(LibDispatchTaskRunnerTest, PostTask) {
+  task_runner_->PostTask(FROM_HERE, BoundRecordTaskOrder(this, "Basic Task"));
+  DispatchLastTask();
+  const char* expectations[] = {
+    "BEGIN Basic Task",
+    "END Basic Task"
+  };
+  VerifyTaskOrder(expectations, arraysize(expectations));
+}
+
+TEST_F(LibDispatchTaskRunnerTest, PostTaskNested) {
+  task_runner_->PostTask(FROM_HERE, base::BindBlock(^{
+      TaskOrderMarker marker(this, "Outer");
+      task_runner_->PostTask(FROM_HERE, BoundRecordTaskOrder(this, "Inner"));
+  }));
+  DispatchLastTask();
+
+  const char* expectations[] = {
+    "BEGIN Outer",
+    "END Outer",
+    "BEGIN Inner",
+    "END Inner"
+  };
+  VerifyTaskOrder(expectations, arraysize(expectations));
+}
+
+TEST_F(LibDispatchTaskRunnerTest, NoMessageLoop) {
+  task_runner_->PostTask(FROM_HERE, base::BindBlock(^{
+      TaskOrderMarker marker(this,
+          base::StringPrintf("MessageLoop = %p", MessageLoop::current()));
+  }));
+  DispatchLastTask();
+
+  const char* expectations[] = {
+    "BEGIN MessageLoop = 0x0",
+    "END MessageLoop = 0x0"
+  };
+  VerifyTaskOrder(expectations, arraysize(expectations));
+}
+
+TEST_F(LibDispatchTaskRunnerTest, DispatchAndPostTasks) {
+  dispatch_async(task_runner_->GetDispatchQueue(), ^{
+      TaskOrderMarker marker(this, "First Block");
+      task_runner_->PostTask(FROM_HERE,
+          BoundRecordTaskOrder(this, "Second Task"));
+  });
+  task_runner_->PostTask(FROM_HERE, BoundRecordTaskOrder(this, "First Task"));
+  dispatch_async(task_runner_->GetDispatchQueue(), ^{
+      TaskOrderMarker marker(this, "Second Block");
+  });
+  DispatchLastTask();
+
+  const char* expectations[] = {
+    "BEGIN First Block",
+    "END First Block",
+    "BEGIN First Task",
+    "END First Task",
+    "BEGIN Second Block",
+    "END Second Block",
+    "BEGIN Second Task",
+    "END Second Task",
+  };
+  VerifyTaskOrder(expectations, arraysize(expectations));
+}
+
+TEST_F(LibDispatchTaskRunnerTest, NonNestable) {
+  task_runner_->PostTask(FROM_HERE, base::BindBlock(^{
+      TaskOrderMarker marker(this, "First");
+      task_runner_->PostNonNestableTask(FROM_HERE, base::BindBlock(^{
+          TaskOrderMarker marker(this, "Third NonNestable");
+      }));
+  }));
+  task_runner_->PostTask(FROM_HERE, BoundRecordTaskOrder(this, "Second"));
+  DispatchLastTask();
+
+  const char* expectations[] = {
+    "BEGIN First",
+    "END First",
+    "BEGIN Second",
+    "END Second",
+    "BEGIN Third NonNestable",
+    "END Third NonNestable"
+  };
+  VerifyTaskOrder(expectations, arraysize(expectations));
+}
+
+TEST_F(LibDispatchTaskRunnerTest, PostDelayed) {
+  base::TimeTicks post_time;
+  __block base::TimeTicks run_time;
+  const base::TimeDelta delta = base::TimeDelta::FromMilliseconds(50);

[Mark Mentovai, 2012/12/06 22:11:45]

These tests with timers are always so shady, but what can you do?

+
+  task_runner_->PostTask(FROM_HERE, BoundRecordTaskOrder(this, "First"));
+  post_time = base::TimeTicks::Now();
+  task_runner_->PostDelayedTask(FROM_HERE, base::BindBlock(^{
+      TaskOrderMarker marker(this, "Timed");
+      run_time = base::TimeTicks::Now();
+      (&message_loop_)->PostTask(FROM_HERE, MessageLoop::QuitClosure());
+  }), delta);
+  task_runner_->PostTask(FROM_HERE, BoundRecordTaskOrder(this, "Second"));
+  message_loop_.Run();
+
+  const char* expectations[] = {
+    "BEGIN First",
+    "END First",
+    "BEGIN Second",
+    "END Second",
+    "BEGIN Timed",
+    "END Timed",
+  };
+  VerifyTaskOrder(expectations, arraysize(expectations));
+
+  EXPECT_GE(run_time, post_time + delta);
+}