* {@link Runnable}s that close them submitted to each one's closing {@link Executor}.
   */
  @VisibleForTesting
  CountDownLatch whenClosedCountDown() {
    return closeables.whenClosedCountDown();
  }

  /** The state of a {@link CloseableList}. */
  enum State {
    /** The {@link CloseableList} has not been subsumed or closed. */
    OPEN,

    /**

   * {@link Runnable}s that close them submitted to each one's closing {@link Executor}.
   */
  @VisibleForTesting
  CountDownLatch whenClosedCountDown() {
    return closeables.whenClosedCountDown();
  }

  /** The state of a {@link CloseableList}. */
  enum State {
    /** The {@link CloseableList} has not been subsumed or closed. */
    OPEN,

    /**

  /** Waits for the given step's closeables to be closed. */
  void waitUntilClosed(ClosingFuture<?> closingFuture) {
    assertTrue(awaitUninterruptibly(closingFuture.whenClosedCountDown(), 1, SECONDS));
  }

  void assertThatFutureFailsWithException(Future<?> future) {
    try {
      getUninterruptibly(future);
      fail("Expected future to fail: " + future);