}
  }

  /** Checks that future.get times out, with the default timeout of {@code timeoutMillis()}. */
  void assertFutureTimesOut(Future<?> future) {
    assertFutureTimesOut(future, timeoutMillis());
  }

  /** Checks that future.get times out, with the given millisecond timeout. */
  void assertFutureTimesOut(Future<?> future, long timeoutMillis) {
    long startTime = System.nanoTime();
    try {