@Test
  public void submitRunnableTest() {
    TestPriorityScheduler testScheduler = new TestPriorityScheduler();
    PrioritySchedulerDefaultPriorityWrapper psw =
        new PrioritySchedulerDefaultPriorityWrapper(testScheduler, TaskPriority.Low);
    psw.submit(DoNothingRunnable.instance());
    assertTrue(testScheduler.submitRunnableCalled);

    // reset and try with priority
    testScheduler.submitRunnableCalled = false;
    psw.submit(DoNothingRunnable.instance(), TaskPriority.High);
    assertTrue(testScheduler.submitRunnableCalled);
  }