MessageProcessor implements Processor<Message<T>, Message<T>>, Subscription { @Override public void cancel() { try { eventSender.send(new Cancel()); } catch (Exception e) { log.error("Erroring cancelling", e); onError(e); } }  @Override void subscribe(Subscriber<? super Message<T>> subscriber); @Override void request(long n); @Override void cancel(); @Override void onNext(Message<T> t); @Override void onError(Throwable t); @Override void onSubscribe(Subscription s); @Override void onComplete();  }
@Test public void cancel() throws Exception { underTest.cancel(); verify(eventSender).send(new Cancel()); }