@Test
public void illegalDemand() {

    new TestKit(actorSystem) {{
        final ActorRef underTest = createSubscriptionManager();
        underTest.tell(createSubscription(1), getRef());
        final String sid = expectMsgClass(SubscriptionCreated.class).getSubscriptionId();
        underTest.tell(RequestFromSubscription.of(sid, 0L, DittoHeaders.empty()), getRef());
        expectMsgClass(SubscriptionFailed.class);
    }};
}