* implementing {@code stopping}. Note, however, that {@code stopping} does not run at exactly the
   * same times as {@code triggerShutdown}.
   */
  protected void triggerShutdown() {}

  /**
   * Returns the {@link Executor} that will be used to run this service. Subclasses may override

      assertTrue(runCalled);
      assertFalse(shutDownCalled);
      shutDownCalled = true;
      assertEquals(expectedShutdownState, state());
    }

    @Override
    protected void triggerShutdown() {
      exitRun.countDown();
    }

    @Override
    protected Executor executor() {
      return exceptionCatchingExecutor;
    }
  }

      assertTrue(runCalled);
      assertFalse(shutDownCalled);
      shutDownCalled = true;
      assertEquals(expectedShutdownState, state());
    }

    @Override
    protected void triggerShutdown() {
      exitRun.countDown();
    }

    @Override
    protected Executor executor() {
      return exceptionCatchingExecutor;
    }
  }

    final CountDownLatch latch = new CountDownLatch(1);

    @Override
    protected void run() throws Exception {
      latch.await();
    }

    @Override
    protected void triggerShutdown() {
      latch.countDown();
    }
  }

  private static class StartFailingService extends AbstractService {
    @Override
    protected void doStart() {
      notifyFailed(EXCEPTION);
    }

    final CountDownLatch latch = new CountDownLatch(1);

    @Override
    protected void run() throws Exception {
      latch.await();
    }

    @Override
    protected void triggerShutdown() {
      latch.countDown();
    }
  }

  private static class StartFailingService extends AbstractService {
    @Override
    protected void doStart() {
      notifyFailed(EXCEPTION);
    }

    SnappyShutdownService(int index) {
      this.index = index;
    }

    @Override
    protected void run() throws Exception {
      latch.await();
    }

    @Override
    protected void triggerShutdown() {
      latch.countDown();
    }

    @Override
    protected String serviceName() {
      return this.getClass().getSimpleName() + "[" + index + "]";
    }
  }

  public void testNulls() {

    SnappyShutdownService(int index) {
      this.index = index;
    }

    @Override
    protected void run() throws Exception {
      latch.await();
    }

    @Override
    protected void triggerShutdown() {
      latch.countDown();
    }

    @Override
    protected String serviceName() {
      return this.getClass().getSimpleName() + "[" + index + "]";
    }
  }

  public void testNulls() {