public void testReturning() throws Exception {
    assertThat(Callables.returning(null).call()).isNull();

    Object value = new Object();
    Callable<Object> callable = Callables.returning(value);
    assertThat(callable.call()).isEqualTo(value);
    // Expect the same value on subsequent calls
    assertThat(callable.call()).isEqualTo(value);
  }

  @J2ktIncompatible
  @GwtIncompatible

  public void testReturning() throws Exception {
    assertThat(Callables.returning(null).call()).isNull();

    Object value = new Object();
    Callable<Object> callable = Callables.returning(value);
    assertThat(callable.call()).isEqualTo(value);
    // Expect the same value on subsequent calls
    assertThat(callable.call()).isEqualTo(value);
  }

  @J2ktIncompatible
  @GwtIncompatible

@GwtCompatible
class TrustedListenableFutureTask<V extends @Nullable Object> extends FluentFuture.TrustedFuture<V>
    implements RunnableFuture<V> {

  static <V extends @Nullable Object> TrustedListenableFutureTask<V> create(
      AsyncCallable<V> callable) {
    return new TrustedListenableFutureTask<>(callable);
  }

  static <V extends @Nullable Object> TrustedListenableFutureTask<V> create(Callable<V> callable) {

    TestExecutor(MockExecutor mock) {
      super(mock);
    }

    @Override
    protected <T> Callable<T> wrapTask(Callable<T> callable) {
      return new WrappedCallable<T>(callable);
    }

    @Override
    protected Runnable wrapTask(Runnable command) {
      return new WrappedRunnable(command);
    }
  }

    }
  }

  private static List<Callable<String>> createTasks(int n) {
    List<Callable<String>> callables = new ArrayList<>();
    for (int i = 0; i < n; i++) {
      callables.add(Callables.returning(RESULT_VALUE + i));
    }
    return callables;
  }

  private static final class WrappedCallable<T> implements Callable<T> {
    private final Callable<T> delegate;

      Callable<T> callable, ListeningExecutorService listeningExecutorService) {
    checkNotNull(callable);
    checkNotNull(listeningExecutorService);
    return () -> listeningExecutorService.submit(callable);
  }

  /**
   * Wraps the given callable such that for the duration of {@link Callable#call} the thread that is
   * running will have the given name.
   *
   * @param callable The callable to wrap

    this.delegate = checkNotNull(delegate);
  }

  /**
   * Wraps a {@code Callable} for submission to the underlying executor. This method is also applied
   * to any {@code Runnable} passed to the default implementation of {@link #wrapTask(Runnable)}.
   */
  protected abstract <T extends @Nullable Object> Callable<T> wrapTask(Callable<T> callable);

  /**

   * <p>Cancellation does not propagate from the output future to a callable that has begun to
   * execute, but if the output future is cancelled before {@link Callable#call()} is invoked,
   * {@link Callable#call()} will not be invoked.
   */
  public <T extends @Nullable Object> ListenableFuture<T> submit(
      Callable<T> callable, Executor executor) {
    checkNotNull(callable);
    checkNotNull(executor);
    return submitAsync(

  }

  @ParametricNullness
  private <T extends @Nullable Object> T callWithTimeout(
      Callable<T> callable, long timeoutDuration, TimeUnit timeoutUnit, boolean amInterruptible)
      throws Exception {
    checkNotNull(callable);
    checkNotNull(timeoutUnit);
    checkPositiveTimeout(timeoutDuration);

    Future<T> future = executor.submit(callable);

    try {
      return amInterruptible

    TestExecutor(MockExecutor mock) {
      super(mock);
    }

    @Override
    protected <T> Callable<T> wrapTask(Callable<T> callable) {
      return new WrappedCallable<T>(callable);
    }

    @Override
    protected Runnable wrapTask(Runnable command) {
      return new WrappedRunnable(command);
    }
  }