/** 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);