final CountDownLatch latch = new CountDownLatch(1);
        deferred.promise().error(error -> latch.countDown());
        assertTrue(latch.await(10, TimeUnit.SECONDS));
    }

    @Test
    public void test_doneAfterReject() throws Exception {
        final Deferred<SuggestResponse> deferred = new Deferred<>();

        Thread th = new Thread(() -> {
            deferred.reject(new Exception());
        });
        th.start();