@Test
public void orderedSlowPath() {

    TestObserver<Integer> to = new TestObserver<Integer>();
    Disposable d = Disposables.empty();
    QueueDrainObserver<Integer, Integer, Integer> qd = createOrdered(to, d);
    to.onSubscribe(Disposables.empty());
    qd.enter();
    qd.onNext(1);
    to.assertEmpty();
}