@Test
public void testErrorDelayed4() {

    final Observable<String> o1 = Observable.create(new TestErrorObservable("one", "two", "three"));
    final Observable<String> o2 = Observable.create(new TestErrorObservable("four", "five", "six"));
    final Observable<String> o3 = Observable.create(new TestErrorObservable("seven", "eight"));
    final Observable<String> o4 = Observable.create(new TestErrorObservable("nine", null));
    @SuppressWarnings("unchecked")
    Observable<String> m = Observable.create(mergeDelayError(o1, o2, o3, o4));
    m.subscribe(stringObserver);
    verify(stringObserver, times(1)).onError(any(NullPointerException.class));
    verify(stringObserver, never()).onCompleted();
    verify(stringObserver, times(1)).onNext("one");
    verify(stringObserver, times(1)).onNext("two");
    verify(stringObserver, times(1)).onNext("three");
    verify(stringObserver, times(1)).onNext("four");
    verify(stringObserver, times(1)).onNext("five");
    verify(stringObserver, times(1)).onNext("six");
    verify(stringObserver, times(1)).onNext("seven");
    verify(stringObserver, times(1)).onNext("eight");
    verify(stringObserver, times(1)).onNext("nine");
}