* across calls to multiple listeners. Specifically, a given listener will have its callbacks
   * invoked in the same order as the underlying service enters those states. Additionally, at most
   * one of the listener's callbacks will execute at once. However, multiple listeners' callbacks
   * may execute concurrently, and listeners may execute in an order different from the one in which
   * they were registered.

   * more futures or adding more {@code directExecutor()} listeners inline -- consider {@link
   * MoreExecutors#directExecutor}. Otherwise, avoid it: See the warnings on the docs for {@code
   * directExecutor}.
   *
   * <p>This is the most general listener interface. For common operations performed using
   * listeners, see {@link Futures}. For a simplified but general listener interface, see {@link

    // Checking isDone and listeners != TOMBSTONE may seem redundant, but our contract for
    // addListener says that listeners execute 'immediate' if the future isDone(). However, our
    // protocol for completing a future is to assign the value field (which sets isDone to true) and
    // then to release waiters, followed by executing afterDone(), followed by releasing listeners.

 * instance contains a list of listeners, each with an associated {@code Executor}, and guarantees
 * that every {@code Runnable} that is {@linkplain #add added} will be executed after {@link
 * #execute()} is called. Any {@code Runnable} added after the call to {@code execute} is still
 * guaranteed to execute. There is no guarantee, however, that listeners will be executed in the

        }

        latch.await(5, TimeUnit.SECONDS);
        executor.shutdown();

        // Verify all listeners were added
        assertEquals(numThreads, fesenClient.onConnectListenerList.size());
    }

    /**
     * Test: Thread-safe listener invocation during connection
     * Verifies that listeners can be added while connect() is executing
     */
    @Test

  // such as BoundedQueueExecutorService to allow extends but it would be nice to make it final to
  // avoid unintended usage.

  // The execution list to hold our listeners.
  private final ExecutionList executionList = new ExecutionList();

  /**
   * Creates a {@code ListenableFutureTask} that will upon running, execute the given {@code
   * Callable}.
   *

    }
  }

  /**
   * This is for covering a case where the ServiceManager would behave strangely if constructed with
   * no service under management. Listeners would never fire because the ServiceManager was healthy
   * and stopped at the same time. This test ensures that listeners fire and isHealthy makes sense.
   */
  public void testEmptyServiceManager() {
    Logger logger = Logger.getLogger(ServiceManager.class.getName());

   * more futures or adding more {@code directExecutor()} listeners inline -- consider {@link
   * MoreExecutors#directExecutor}. Otherwise, avoid it: See the warnings on the docs for {@code
   * directExecutor}.
   *
   * <p>This is the most general listener interface. For common operations performed using
   * listeners, see {@link Futures}. For a simplified but general listener interface, see {@link

    task.cancel(false);
    assertTrue(task.isDone());
    assertTrue(task.isCancelled());
    assertEquals(1, runLatch.getCount());

    // Wait for the listeners to be called, don't rely on the same-thread exec.
    listenerLatch.await(5, SECONDS);
    assertTrue(task.isDone());
    assertTrue(task.isCancelled());

    // Make sure we didn't run anything.

    }
  }

  /**
   * This is for covering a case where the ServiceManager would behave strangely if constructed with
   * no service under management. Listeners would never fire because the ServiceManager was healthy
   * and stopped at the same time. This test ensures that listeners fire and isHealthy makes sense.
   */
  public void testEmptyServiceManager() {
    Logger logger = Logger.getLogger(ServiceManager.class.getName());