private final Queue<Consumer<RESPONSE>> doneCallbacks = new LinkedBlockingQueue<>();

    private final Queue<Consumer<Throwable>> errorCallbacks = new LinkedBlockingQueue<>();

    private final CountDownLatch latch = new CountDownLatch(1);

    /**
     * Resolves the deferred computation with the given response.
     * @param r The response.
     */
    public void resolve(final RESPONSE r) {

            numObInputDoc.set(response.getNumberOfInputDocs());
            latch.countDown();
        }).error(t -> {
            t.printStackTrace();
            latch.countDown();
            fail();
        });
        latch.await();
        assertEquals(num, numObInputDoc.get());