static void register(Object referent, CountDownLatch latch) {
      references.add(new FinalizableReference(referent, latch));
    }

    final CountDownLatch latch;

    FinalizableReference(Object referent, CountDownLatch latch) {
      super(referent, referenceQueue);
      this.latch = latch;
    }

    @Override
    public void finalizeReferent() {

  public void testAwaitWithNoWait() {
    Stopwatch stopwatch = Stopwatch.createStarted();
    CountDownLatch latch = new CountDownLatch(0);
    awaitUninterruptibly(latch);
    assertTrue(awaitUninterruptibly(latch, 0, MILLISECONDS));
    assertTrue(awaitUninterruptibly(latch, -42, MILLISECONDS));
    assertTrue(awaitUninterruptibly(latch, LONG_DELAY_MS, MILLISECONDS));
    assertTimeNotPassed(stopwatch, LONG_DELAY_MS);
  }

    // thread because the task will block on the task latch after unblocking
    // the run latch.
    exec.execute(task);
    runLatch.await();
    assertEquals(1, listenerLatch.getCount());
    assertFalse(task.isDone());
    assertFalse(task.isCancelled());

    // Finish the task by unblocking the task latch.  Then wait for the
    // listener to be called by blocking on the listener latch.
    taskLatch.countDown();

      queue.enqueue(incrementingEvent(counters, listener, 4));
      queue.enqueue(countDownEvent(latch));
      assertEquals(0, counters.size());
      queue.dispatch();
      latch.await();
      assertEquals(multiset(listener, 4), counters);
    } finally {
      service.shutdown();
    }
  }

  public void testEnqueueAndDispatch_multithreaded_withThrowingRunnable()

      queue.enqueue(incrementingEvent(counters, listener, 4));
      queue.enqueue(countDownEvent(latch));
      assertEquals(0, counters.size());
      queue.dispatch();
      latch.await();
      assertEquals(multiset(listener, 4), counters);
    } finally {
      service.shutdown();
    }
  }

  public void testEnqueueAndDispatch_multithreaded_withThrowingRunnable()

  public void testAwaitWithNoWait() {
    Stopwatch stopwatch = Stopwatch.createStarted();
    CountDownLatch latch = new CountDownLatch(0);
    awaitUninterruptibly(latch);
    assertTrue(awaitUninterruptibly(latch, 0, MILLISECONDS));
    assertTrue(awaitUninterruptibly(latch, -42, MILLISECONDS));
    assertTrue(awaitUninterruptibly(latch, LONG_DELAY_MS, MILLISECONDS));
    assertTimeNotPassed(stopwatch, LONG_DELAY_MS);
  }

    static void register(Object referent, CountDownLatch latch) {
      references.add(new FinalizableReference(referent, latch));
    }

    final CountDownLatch latch;

    FinalizableReference(Object referent, CountDownLatch latch) {
      super(referent, referenceQueue);
      this.latch = latch;
    }

    @Override
    public void finalizeReferent() {

  private final ListenableFuture<?> future;
  private final CountDownLatch latch;

  public ListenableFutureTester(ListenableFuture<?> future) {
    this.exec = newCachedThreadPool();
    this.future = checkNotNull(future);
    this.latch = new CountDownLatch(1);
  }

  public void setUp() {
    future.addListener(latch::countDown, exec);

    assertEquals(1, latch.getCount());
    assertFalse(future.isDone());

    // thread because the task will block on the task latch after unblocking
    // the run latch.
    exec.execute(task);
    runLatch.await();
    assertEquals(1, listenerLatch.getCount());
    assertFalse(task.isDone());
    assertFalse(task.isCancelled());

    // Finish the task by unblocking the task latch.  Then wait for the
    // listener to be called by blocking on the listener latch.
    taskLatch.countDown();

  private final ListenableFuture<?> future;
  private final CountDownLatch latch;

  public ListenableFutureTester(ListenableFuture<?> future) {
    this.exec = newCachedThreadPool();
    this.future = checkNotNull(future);
    this.latch = new CountDownLatch(1);
  }

  public void setUp() {
    future.addListener(latch::countDown, exec);

    assertEquals(1, latch.getCount());
    assertFalse(future.isDone());