tester.testForwarding(
        Runnable.class,
        new Function<Runnable, Runnable>() {
          @Override
          public Runnable apply(Runnable runnable) {
            return new ForwardingRunnable(runnable);
          }
        });
  }

  public void testToStringForwarding() {
    tester.testForwarding(
        Runnable.class,
        new Function<Runnable, Runnable>() {
          @Override

  enum WorkerRunningState {
    /** Runnable is not running and not queued for execution */
    IDLE,
    /** Runnable is not running, but is being queued for execution */
    QUEUING,
    /** runnable has been submitted but has not yet begun execution */
    QUEUED,
    RUNNING,
  }

  /** Underlying executor that all submitted Runnable objects are run on. */
  private final Executor executor;

            }
            runCalled.getAndIncrement();
          }
        },
        directExecutor());
    Runnable execute =
        new Runnable() {
          @Override
          public void run() {
            list.execute();
          }
        };
    Thread thread1 = new Thread(execute);
    Thread thread2 = new Thread(execute);
    thread1.start();
    thread2.start();

    }

    @Override
    public T call() throws Exception {
      return delegate.call();
    }
  }

  private static final class WrappedRunnable implements Runnable {
    private final Runnable delegate;

    WrappedRunnable(Runnable delegate) {
      this.delegate = delegate;
    }

    @Override
    public void run() {
      delegate.run();
    }
  }

            }
            runCalled.getAndIncrement();
          }
        },
        directExecutor());
    Runnable execute =
        new Runnable() {
          @Override
          public void run() {
            list.execute();
          }
        };
    Thread thread1 = new Thread(execute);
    Thread thread2 = new Thread(execute);
    thread1.start();
    thread2.start();

  private val loggingUncaughtExceptionHandler =
    UncaughtExceptionHandler { _, throwable ->
      log.put("uncaught exception: $throwable")
    }

  private val threadFactory =
    ThreadFactory { runnable ->
      Thread(runnable, "TaskRunnerRealBackendTest").apply {
        isDaemon = true
        uncaughtExceptionHandler = loggingUncaughtExceptionHandler
      }
    }

  private val backend = TaskRunner.RealBackend(threadFactory)

    ListenableFuture<?> future;

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

    runnable = new ThrowingRunnable(5, ex);
    future = service.scheduleWithFixedDelay(runnable, 1, 1, MILLISECONDS);

      Runnable runnable, @ParametricNullness V result) {
    return new ListenableFutureTask<>(runnable, result);
  }

  ListenableFutureTask(Callable<V> callable) {
    super(callable);
  }

  ListenableFutureTask(Runnable runnable, @ParametricNullness V result) {
    super(runnable, result);
  }

  @Override
  public void addListener(Runnable listener, Executor exec) {

   * @throws UncheckedExecutionException if {@code runnable} throws a {@code RuntimeException}
   * @throws ExecutionError if {@code runnable} throws an {@code Error}
   * @since 22.0
   */
  void runWithTimeout(Runnable runnable, long timeoutDuration, TimeUnit timeoutUnit)
      throws TimeoutException, InterruptedException;

  /**
   * Invokes a specified Runnable, timing out after the specified time limit. If the target method

      Runnable runnable, @ParametricNullness V result) {
    return new ListenableFutureTask<>(runnable, result);
  }

  ListenableFutureTask(Callable<V> callable) {
    super(callable);
  }

  ListenableFutureTask(Runnable runnable, @ParametricNullness V result) {
    super(runnable, result);
  }

  @Override
  public void addListener(Runnable listener, Executor exec) {