}
        };

    List<Throwable> exceptions = runThreadsAndReturnExceptions(numThreads, task);

    assertThat(exceptions).isEmpty();
  }

  private static List<Throwable> runThreadsAndReturnExceptions(int numThreads, Runnable task) {
    List<Thread> threads = new ArrayList<>(numThreads);
    final List<Throwable> exceptions = new ArrayList<>(numThreads);
    for (int i = 0; i < numThreads; i++) {

    }

    abstract boolean isPermitted(Exception exception);

    void assertPermitted(Exception exception) {
      if (!isPermitted(exception)) {
        String message =
            "Exception "
                + exception.getClass().getSimpleName()
                + " was thrown; expected "
                + getMessage();
        Helpers.fail(exception, message);
      }
    }

 *       will be thrown.
 *   <li>If no exceptions or errors were thrown in the try block, the <i>first</i> exception thrown
 *       by an attempt to close a resource will be thrown.
 *   <li>Any exception caught when attempting to close a resource that is <i>not</i> thrown (because
 *       another exception is already being thrown) is <i>suppressed</i>.
 * </ul>
 *

   *   <li>To treat {@link InterruptedException} uniformly with other exceptions, use {@link
   *       Futures#getChecked(Future, Class) Futures.getChecked}.
   *   <li>To get uninterruptibility and remove checked exceptions, use {@link
   *       Futures#getUnchecked}.
   * </ul>
   *
   * @throws ExecutionException if the computation threw an exception
   * @throws CancellationException if the computation was cancelled
   */

    }

    abstract boolean isPermitted(Exception exception);

    void assertPermitted(Exception exception) {
      if (!isPermitted(exception)) {
        String message =
            "Exception "
                + exception.getClass().getSimpleName()
                + " was thrown; expected "
                + getMessage();
        Helpers.fail(exception, message);
      }
    }

    try {
      in.copyTo(out);
      fail();
    } catch (IOException expected) {
    }
  }

  /**
   * @return the number of exceptions that were suppressed on the expected thrown exception
   */
  private static int runSuppressionFailureTest(ByteSource in, ByteSink out) {
    try {
      in.copyTo(out);
      fail();
    } catch (IOException expected) {

    try {
      in.copyTo(out);
      fail();
    } catch (IOException expected) {
    }
  }

  /**
   * @return the number of exceptions that were suppressed on the expected thrown exception
   */
  private static int runSuppressionFailureTest(CharSource in, CharSink out) {
    try {
      in.copyTo(out);
      fail();
    } catch (IOException expected) {

          }
        };

    List<Throwable> exceptions = runThreadsAndReturnExceptions(numThreads, task);

    assertThat(exceptions).isEmpty();
  }

  private static List<Throwable> runThreadsAndReturnExceptions(int numThreads, Runnable task) {
    List<Thread> threads = new ArrayList<>(numThreads);
    final List<Throwable> exceptions = new ArrayList<>(numThreads);
    for (int i = 0; i < numThreads; i++) {

    try {
      in.copyTo(out);
      fail();
    } catch (IOException expected) {
    }
  }

  /**
   * @return the number of exceptions that were suppressed on the expected thrown exception
   */
  private static int runSuppressionFailureTest(ByteSource in, ByteSink out) {
    try {
      in.copyTo(out);
      fail();
    } catch (IOException expected) {

  }

  /** Simple logging handler for subscriber exceptions. */
  static final class LoggingHandler implements SubscriberExceptionHandler {
    static final LoggingHandler INSTANCE = new LoggingHandler();

    @Override
    public void handleException(Throwable exception, SubscriberExceptionContext context) {
      Logger logger = logger(context);