* submitted tasks and to collections of tasks submitted via {@code invokeAll}, {@code invokeAny},
   * {@code schedule}, {@code scheduleAtFixedRate}, and {@code scheduleWithFixedDelay}. In the case
   * of tasks submitted by {@code invokeAll} or {@code invokeAny}, tasks will run serially on the
   * calling thread. Tasks are run to completion before a {@code Future} is returned to the caller

   * submitted tasks and to collections of tasks submitted via {@code invokeAll}, {@code invokeAny},
   * {@code schedule}, {@code scheduleAtFixedRate}, and {@code scheduleWithFixedDelay}. In the case
   * of tasks submitted by {@code invokeAll} or {@code invokeAny}, tasks will run serially on the
   * calling thread. Tasks are run to completion before a {@code Future} is returned to the caller

    return delegate.scheduleAtFixedRate(wrapTask(command), initialDelay, period, unit);
  }

  @Override
  public final ScheduledFuture<?> scheduleWithFixedDelay(
      Runnable command, long initialDelay, long delay, TimeUnit unit) {
    return delegate.scheduleWithFixedDelay(wrapTask(command), initialDelay, delay, unit);
  }

  final ScheduledExecutorService executor =
      new ScheduledThreadPoolExecutor(10) {
        @Override
        public ScheduledFuture<?> scheduleWithFixedDelay(
            Runnable command, long initialDelay, long delay, TimeUnit unit) {
          return future = super.scheduleWithFixedDelay(command, initialDelay, delay, unit);
        }
      };

  public void testServiceStartStop() throws Exception {

  final ScheduledExecutorService executor =
      new ScheduledThreadPoolExecutor(10) {
        @Override
        public ScheduledFuture<?> scheduleWithFixedDelay(
            Runnable command, long initialDelay, long delay, TimeUnit unit) {
          return future = super.scheduleWithFixedDelay(command, initialDelay, delay, unit);
        }
      };

  public void testServiceStartStop() throws Exception {

      Runnable command, long initialDelay, long period, TimeUnit unit);

  /** @since 15.0 (previously returned ScheduledFuture) */
  @Override
  ListenableScheduledFuture<?> scheduleWithFixedDelay(
      Runnable command, long initialDelay, long delay, TimeUnit unit);

    assertExecutionException(future, ex);
    assertEquals(5, runnable.count);
    assertEquals(0, delegate.getQueue().size());

    runnable = new ThrowingRunnable(5, ex);
    future = service.scheduleWithFixedDelay(runnable, 1, 1, TimeUnit.MILLISECONDS);
    assertExecutionException(future, ex);
    assertEquals(5, runnable.count);
    assertEquals(0, delegate.getQueue().size());
  }

    assertExecutionException(future, ex);
    assertEquals(5, runnable.count);
    assertEquals(0, delegate.getQueue().size());

    runnable = new ThrowingRunnable(5, ex);
    future = service.scheduleWithFixedDelay(runnable, 1, 1, TimeUnit.MILLISECONDS);
    assertExecutionException(future, ex);
    assertEquals(5, runnable.count);
    assertEquals(0, delegate.getQueue().size());
  }

   * @author Luke Sandberg
   * @since 11.0
   */
  public abstract static class Scheduler {
    /**
     * Returns a {@link Scheduler} that schedules the task using the {@link
     * ScheduledExecutorService#scheduleWithFixedDelay} method.
     *
     * @param initialDelay the time to delay first execution
     * @param delay the delay between the termination of one execution and the commencement of the
     *     next

    }

    @Override
    public ListenableScheduledFuture<?> scheduleWithFixedDelay(
        Runnable command, long initialDelay, long delay, TimeUnit unit) {
      NeverSuccessfulListenableFutureTask task = new NeverSuccessfulListenableFutureTask(command);
      ScheduledFuture<?> scheduled =
          delegate.scheduleWithFixedDelay(task, initialDelay, delay, unit);