@Test
 public void testFulfillAdaptedSubscriber() {
   MySubscriber<String> subscriber = new MySubscriber<>();
   Handler<AsyncResult<String>> o = RxHelper.toFuture(subscriber);
   o.handle(Future.succeededFuture("abc"));
   subscriber.assertItem("abc").assertCompleted().assertEmpty();
 }
 @Test
 public void testFulfillAdaptedFunctions2() {
   MySubscriber<String> subscriber = new MySubscriber<>();
   Handler<AsyncResult<String>> o = RxHelper.toFuture(subscriber::onNext, subscriber::onError);
   o.handle(Future.succeededFuture("abc"));
   subscriber.assertItem("abc").assertEmpty();
 }
 @Test
 public void testCompleteWithSuccessBeforeSubscribe() {
   ObservableFuture<String> o = RxHelper.observableFuture();
   o.toHandler().handle(Future.succeededFuture("abc"));
   MySubscriber<String> subscriber = new MySubscriber<>();
   o.subscribe(subscriber);
   subscriber.assertItem("abc").assertCompleted().assertEmpty();
 }