@Override
        public String toString() {
          return "running()";
        }
      };
  private static final ListenerCallQueue.Event<Listener> STOPPING_FROM_STARTING_EVENT =
      stoppingEvent(STARTING);
  private static final ListenerCallQueue.Event<Listener> STOPPING_FROM_RUNNING_EVENT =
      stoppingEvent(RUNNING);

  private static final ListenerCallQueue.Event<Listener> TERMINATED_FROM_NEW_EVENT =
      terminatedEvent(NEW);

    assertLessThan(NEW, TERMINATED);

    assertLessThan(STARTING, RUNNING);
    assertLessThan(STARTING, STOPPING);
    assertLessThan(STARTING, FAILED);

    assertLessThan(RUNNING, STOPPING);
    assertLessThan(RUNNING, FAILED);

    assertLessThan(STOPPING, FAILED);
    assertLessThan(STOPPING, TERMINATED);
  }

  private static <T extends Comparable<? super T>> void assertLessThan(T a, T b) {

    assertFalse(service.isRunning());
    assertTrue(service.doStartCalled);

    service.stopAsync();
    assertEquals(State.STOPPING, service.state());
    assertFalse(service.isRunning());
    assertFalse(service.doStopCalled);

    service.notifyStarted();
    assertEquals(State.STOPPING, service.state());
    assertFalse(service.isRunning());
    assertTrue(service.doStopCalled);

    service.notifyStopped();

    assertFalse(service.isRunning());
    assertTrue(service.doStartCalled);

    service.stopAsync();
    assertEquals(State.STOPPING, service.state());
    assertFalse(service.isRunning());
    assertFalse(service.doStopCalled);

    service.notifyStarted();
    assertEquals(State.STOPPING, service.state());
    assertFalse(service.isRunning());
    assertTrue(service.doStopCalled);

    service.notifyStopped();

    assertLessThan(NEW, TERMINATED);

    assertLessThan(STARTING, RUNNING);
    assertLessThan(STARTING, STOPPING);
    assertLessThan(STARTING, FAILED);

    assertLessThan(RUNNING, STOPPING);
    assertLessThan(RUNNING, FAILED);

    assertLessThan(STOPPING, FAILED);
    assertLessThan(STOPPING, TERMINATED);
  }

  private static <T extends Comparable<? super T>> void assertLessThan(T a, T b) {

     * Called when the service transitions to the {@linkplain State#STOPPING STOPPING} state. The
     * only valid values for {@code from} are {@linkplain State#STARTING STARTING} or {@linkplain
     * State#RUNNING RUNNING}. This occurs when {@link Service#stopAsync} is called.
     *
     * @param from The previous state that is being transitioned from.
     */
    public void stopping(State from) {}

    /**

    assertFalse(service.startUpCalled);

    service.startAsync().awaitRunning();
    assertTrue(service.startUpCalled);
    assertEquals(Service.State.RUNNING, service.state());

    enterRun.await(); // to avoid stopping the service until run() is invoked

    service.stopAsync().awaitTerminated();
    assertTrue(service.shutDownCalled);
    assertEquals(Service.State.TERMINATED, service.state());
    executionThread.join();
  }

    assertEquals(1, service.shutDownCalled);
    assertEquals(Service.State.TERMINATED, service.state());
    assertThat(service.transitionStates)
        .containsExactly(Service.State.STARTING, Service.State.STOPPING)
        .inOrder();
  }

  public void testStop_failed() {
    final Exception exception = new Exception("deliberate");
    TestService service =
        new TestService() {
          @Override

   * blocks, it can prevent this service from changing state. If you need to performing a blocking
   * operation in order to trigger shutdown, consider instead registering a listener and
   * implementing {@code stopping}. Note, however, that {@code stopping} does not run at exactly the
   * same times as {@code triggerShutdown}.
   */
  protected void triggerShutdown() {}

  /**

    assertFalse(service.startUpCalled);

    service.startAsync().awaitRunning();
    assertTrue(service.startUpCalled);
    assertEquals(Service.State.RUNNING, service.state());

    enterRun.await(); // to avoid stopping the service until run() is invoked

    service.stopAsync().awaitTerminated();
    assertTrue(service.shutDownCalled);
    assertEquals(Service.State.TERMINATED, service.state());
    executionThread.join();
  }