return i;
          }
        };

    List<Future<Integer>> futures = executor.invokeAll(Collections.nCopies(10, incrementTask));

    for (int i = 0; i < 10; i++) {
      Future<Integer> future = futures.get(i);
      assertTrue("Task should have been run before being returned", future.isDone());
      assertEquals(i, future.get().intValue());
    }

  @CanIgnoreReturnValue
  protected boolean setFuture(ListenableFuture<? extends V> future) {
    checkNotNull(future);

    // If this future is already cancelled, cancel the delegate.
    // TODO(cpovirk): Should we do this at the end of the method, as in the server version?
    // TODO(cpovirk): Use maybePropagateCancellationTo?
    if (isCancelled()) {
      future.cancel(mayInterruptIfRunning);
    }

    assertThat(future.isDone()).isFalse();
    assertThat(future.set(1)).isTrue();
    assertSuccessful(future, 1);
  }

  public void testSetFutureNull() throws Exception {
    assertThrows(NullPointerException.class, () -> future.setFuture(null));

    assertThat(future.isDone()).isFalse();
    assertThat(future.set(1)).isTrue();

  }

  /**
   * Invokes {@code future.}{@link Future#get() get()} uninterruptibly.
   *
   * <p>Similar methods:
   *
   * <ul>
   *   <li>To retrieve a result from a {@code Future} that is already done, use {@link
   *       Futures#getDone Futures.getDone}.
   *   <li>To treat {@link InterruptedException} uniformly with other exceptions, use {@link
   *       Futures#getChecked(Future, Class) Futures.getChecked}.

  @CanIgnoreReturnValue
  @ParametricNullness
  static <V extends @Nullable Object, X extends Exception> V getChecked(
      Future<V> future, Class<X> exceptionClass) throws X {
    return getChecked(bestGetCheckedTypeValidator(), future, exceptionClass);
  }

  /** Implementation of {@link Futures#getChecked(Future, Class)}. */
  @CanIgnoreReturnValue
  @VisibleForTesting
  @ParametricNullness

      List<Future<String>> futures = testExecutor.invokeAll(tasks);
      mock.assertLastMethodCalled("invokeAll");
      checkResults(futures);
    }
    {
      MockExecutor mock = new MockExecutor();
      TimeUnit unit = SECONDS;
      long timeout = 5;
      TestExecutor testExecutor = new TestExecutor(mock);
      List<Future<String>> futures = testExecutor.invokeAll(tasks, timeout, unit);

   * Future} instances to be upgraded to {@code ListenableFuture} after the fact.
   */
  public static <V extends @Nullable Object> ListenableFuture<V> listenInPoolThread(
      Future<V> future) {
    if (future instanceof ListenableFuture) {
      return (ListenableFuture<V>) future;
    }
    return new ListenableFutureAdapter<>(future);
  }

  /**

    final SettableFuture<@Nullable Void> future = SettableFuture.create();
    Object unused =
        new Object() {
          @SuppressWarnings({"removal", "Finalize"}) // b/260137033
          @Override
          protected void finalize() {
            future.set(null);
          }
        };
    unused = null; // Hint to the JIT that unused is unreachable
    GcFinalization.awaitDone(future);
    assertTrue(future.isDone());

    }
  }

  private enum Result {
    SUCCESS(immediateFuture(new Object())),
    FAILURE(immediateFailedFuture(new Exception()));

    final Future<Object> future;

    Result(Future<Object> result) {
      this.future = result;
    }
  }

  private enum ExceptionType {
    CHECKED(IOException.class),
    UNCHECKED(RuntimeException.class);

    SettableFuture<Integer> future = SettableFuture.create();
    assertTrue(future.set(42));
    // Later attempts to set the future should return false.
    assertFalse(future.set(23));
    assertFalse(future.setException(new Exception("bar")));
    assertFalse(future.setFuture(SettableFuture.<Integer>create()));
    // Check that the future has been set properly.
    assertTrue(future.isDone());
    assertFalse(future.isCancelled());