src/base/test/task_runner_test_template.h

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 // This class defines tests that implementations of TaskRunner should
   6 // pass in order to be conformant.  Here's how you use it to test your
   7 // implementation.
   8 //
   9 // Say your class is called MyTaskRunner.  Then you need to define a
  10 // class called MyTaskRunnerTestDelegate in my_task_runner_unittest.cc
  11 // like this:
  12 //
  13 //   class MyTaskRunnerTestDelegate {
  14 //    public:
  15 //     // Tasks posted to the task runner after this and before
  16 //     // StopTaskRunner() is called is called should run successfully.
  17 //     void StartTaskRunner() {
  18 //       ...
  19 //     }
  20 //
  21 //     // Should return the task runner implementation.  Only called
  22 //     // after StartTaskRunner and before StopTaskRunner.
  23 //     scoped_refptr<MyTaskRunner> GetTaskRunner() {
  24 //       ...
  25 //     }
  26 //
  27 //     // Stop the task runner and make sure all tasks posted before
  28 //     // this is called are run. Caveat: delayed tasks are not run,
  29        // they're simply deleted.
  30 //     void StopTaskRunner() {
  31 //       ...
  32 //     }
  33 //
  34 //     // Returns whether or not the task runner obeys non-zero delays.
  35 //     bool TaskRunnerHandlesNonZeroDelays() const {
  36 //       return true;
  37 //     }
  38 //   };
  39 //
  40 // The TaskRunnerTest test harness will have a member variable of
  41 // this delegate type and will call its functions in the various
  42 // tests.
  43 //
  44 // Then you simply #include this file as well as gtest.h and add the
  45 // following statement to my_task_runner_unittest.cc:
  46 //
  47 //   INSTANTIATE_TYPED_TEST_CASE_P(
  48 //       MyTaskRunner, TaskRunnerTest, MyTaskRunnerTestDelegate);
  49 //
  50 // Easy!
  51
  52 #ifndef BASE_TEST_TASK_RUNNER_TEST_TEMPLATE_H_
  53 #define BASE_TEST_TASK_RUNNER_TEST_TEMPLATE_H_
  54
  55 #include <cstddef>
  56 #include <map>
  57
  58 #include "base/basictypes.h"
  59 #include "base/bind.h"
  60 #include "base/callback.h"
  61 #include "base/memory/ref_counted.h"
  62 #include "base/synchronization/condition_variable.h"
  63 #include "base/synchronization/lock.h"
  64 #include "base/task_runner.h"
  65 #include "base/threading/thread.h"
  66 #include "base/tracked_objects.h"
  67 #include "testing/gtest/include/gtest/gtest.h"
  68
  69 namespace base {
  70
  71 namespace internal {
  72
  73 // Utility class that keeps track of how many times particular tasks
  74 // are run.
  75 class TaskTracker : public RefCountedThreadSafe<TaskTracker> {
  76  public:
  77   TaskTracker();
  78
  79   // Returns a closure that runs the given task and increments the run
  80   // count of |i| by one.  |task| may be null.  It is guaranteed that
  81   // only one task wrapped by a given tracker will be run at a time.
  82   Closure WrapTask(const Closure& task, int i);
  83
  84   std::map<int, int> GetTaskRunCounts() const;
  85
  86   // Returns after the tracker observes a total of |count| task completions.
  87   void WaitForCompletedTasks(int count);
  88
  89  private:
  90   friend class RefCountedThreadSafe<TaskTracker>;
  91
  92   ~TaskTracker();
  93
  94   void RunTask(const Closure& task, int i);
  95
  96   mutable Lock lock_;
  97   std::map<int, int> task_run_counts_;
  98   int task_runs_;
  99   ConditionVariable task_runs_cv_;
 100
 101   DISALLOW_COPY_AND_ASSIGN(TaskTracker);
 102 };
 103
 104 }  // namespace internal
 105
 106 template <typename TaskRunnerTestDelegate>
 107 class TaskRunnerTest : public testing::Test {
 108  protected:
 109   TaskRunnerTest() : task_tracker_(new internal::TaskTracker()) {}
 110
 111   const scoped_refptr<internal::TaskTracker> task_tracker_;
 112   TaskRunnerTestDelegate delegate_;
 113 };
 114
 115 TYPED_TEST_CASE_P(TaskRunnerTest);
 116
 117 // We can't really test much, since TaskRunner provides very few
 118 // guarantees.
 119
 120 // Post a bunch of tasks to the task runner.  They should all
 121 // complete.
 122 TYPED_TEST_P(TaskRunnerTest, Basic) {
 123   std::map<int, int> expected_task_run_counts;
 124
 125   this->delegate_.StartTaskRunner();
 126   scoped_refptr<TaskRunner> task_runner = this->delegate_.GetTaskRunner();
 127   // Post each ith task i+1 times.
 128   for (int i = 0; i < 20; ++i) {
 129     const Closure& ith_task = this->task_tracker_->WrapTask(Closure(), i);
 130     for (int j = 0; j < i + 1; ++j) {
 131       task_runner->PostTask(FROM_HERE, ith_task);
 132       ++expected_task_run_counts[i];
 133     }
 134   }
 135   this->delegate_.StopTaskRunner();
 136
 137   EXPECT_EQ(expected_task_run_counts,
 138             this->task_tracker_->GetTaskRunCounts());
 139 }
 140
 141 // Post a bunch of delayed tasks to the task runner.  They should all
 142 // complete.
 143 TYPED_TEST_P(TaskRunnerTest, Delayed) {
 144   if (!this->delegate_.TaskRunnerHandlesNonZeroDelays()) {
 145     DLOG(INFO) << "This TaskRunner doesn't handle non-zero delays; skipping";
 146     return;
 147   }
 148
 149   std::map<int, int> expected_task_run_counts;
 150   int expected_total_tasks = 0;
 151
 152   this->delegate_.StartTaskRunner();
 153   scoped_refptr<TaskRunner> task_runner = this->delegate_.GetTaskRunner();
 154   // Post each ith task i+1 times with delays from 0-i.
 155   for (int i = 0; i < 20; ++i) {
 156     const Closure& ith_task = this->task_tracker_->WrapTask(Closure(), i);
 157     for (int j = 0; j < i + 1; ++j) {
 158       task_runner->PostDelayedTask(
 159           FROM_HERE, ith_task, base::TimeDelta::FromMilliseconds(j));
 160       ++expected_task_run_counts[i];
 161       ++expected_total_tasks;
 162     }
 163   }
 164   this->task_tracker_->WaitForCompletedTasks(expected_total_tasks);
 165   this->delegate_.StopTaskRunner();
 166
 167   EXPECT_EQ(expected_task_run_counts,
 168             this->task_tracker_->GetTaskRunCounts());
 169 }
 170
 171 namespace internal {
 172
 173 // Calls RunsTasksOnCurrentThread() on |task_runner| and expects it to
 174 // equal |expected_value|.
 175 void ExpectRunsTasksOnCurrentThread(
 176     bool expected_value,
 177     const scoped_refptr<TaskRunner>& task_runner);
 178
 179 }  // namespace internal
 180
 181 // Post a bunch of tasks to the task runner as well as to a separate
 182 // thread, each checking the value of RunsTasksOnCurrentThread(),
 183 // which should return true for the tasks posted on the task runner
 184 // and false for the tasks posted on the separate thread.
 185 TYPED_TEST_P(TaskRunnerTest, RunsTasksOnCurrentThread) {
 186   std::map<int, int> expected_task_run_counts;
 187
 188   Thread thread("Non-task-runner thread");
 189   ASSERT_TRUE(thread.Start());
 190   this->delegate_.StartTaskRunner();
 191
 192   scoped_refptr<TaskRunner> task_runner = this->delegate_.GetTaskRunner();
 193   // Post each ith task i+1 times on the task runner and i+1 times on
 194   // the non-task-runner thread.
 195   for (int i = 0; i < 20; ++i) {
 196     const Closure& ith_task_runner_task =
 197         this->task_tracker_->WrapTask(
 198             Bind(&internal::ExpectRunsTasksOnCurrentThread,
 199                  true, task_runner),
 200             i);
 201     const Closure& ith_non_task_runner_task =
 202         this->task_tracker_->WrapTask(
 203             Bind(&internal::ExpectRunsTasksOnCurrentThread,
 204                  false, task_runner),
 205             i);
 206     for (int j = 0; j < i + 1; ++j) {
 207       task_runner->PostTask(FROM_HERE, ith_task_runner_task);
 208       thread.message_loop()->PostTask(FROM_HERE, ith_non_task_runner_task);
 209       expected_task_run_counts[i] += 2;
 210     }
 211   }
 212
 213   this->delegate_.StopTaskRunner();
 214   thread.Stop();
 215
 216   EXPECT_EQ(expected_task_run_counts,
 217             this->task_tracker_->GetTaskRunCounts());
 218 }
 219
 220 REGISTER_TYPED_TEST_CASE_P(
 221     TaskRunnerTest, Basic, Delayed, RunsTasksOnCurrentThread);
 222
 223 }  // namespace base
 224
 225 #endif  //#define BASE_TEST_TASK_RUNNER_TEST_TEMPLATE_H_