Unit Testing: How to verify and mock onCompleted for an Observable in RxJava within Android

I am trying to write some unit tests for an Android application that is using Retrofit 2, Mockito 1.10 and RXJava 1.0. I am not using a java version that supports lambdas!

My code uses Observables and I can do the following:

when(myAPI.Complete(anyString(), any(MyContainer.class)))
        .thenReturn(Observable.<GenericResponse>error(new Throwable("An error has occurred!")));

Subscriber genericResponseSubscriber = mock(Subscriber.class);

myPresenter.myUseCase(id, container, genericResponseSubscriber);

verify(genericResponseSubscriber, times(1)).onError(any(Throwable.class));

The above code works fine and allows me to throw an error and capture it within the test.

What I need to be able to do as well (of course) :) is to capture positive conditions. I feel like it's obvious but can't find the answer I need.

How can I capture onComplete and onNext cases ?

I know that the verification for onComplete would be...

verify(genericResponseSubscriber, times(1)).onCompleted();

But I can't see what my 'when' clause should be. I tried the following but that fails:

GenericResponse response = new GenericResponse();
response.setSuccess(true);

when(myAPI.orderComplete(anyString(), any(MyContainer.class)))
        .thenReturn(Observable.just(response));

Subscriber genericResponseSubscriber = mock(Subscriber.class);

myPresenter.myUseCase(id, container, genericResponseSubscriber);

verify(genericResponseSubscriber, times(1)).onCompleted();

The failure here is that subscriber.onStart() was instead called.

So, what I would like to know is, how I can mock and verify the 'onComplete' and 'onNext' calls, please and more importantly what I should have looked to be able to have resolved this myself rather than having to ask! :)

As always, any help is appreciated.

Edit..

My onError working test case..

    public void UseCaseOnError() throws Exception {
        
     String id = "5";
    
        
     order Order = new Order();
        
     SomeContainer myContainer = new SomeContainer(order);
    
        

     when(myRetroFitAPI.complete(anyString(), any(SomeContainer.class)))

.thenReturn(Observable.error(new Throwable(“My error!")));
 


     Subscriber genericResponseSubscriber = mock(Subscriber.class);
    
        

     orderPresenter.doUseCase(id, myContainer, genericResponseSubscriber);
    
        

     verify(genericResponseSubscriber,times(1)).onError(any(Throwable.class));
    
    

}

What I should really add is that, I feel there should be an equivalent for onError in terms of a positive state, i.e. onCompleted. If I do the same but with onCompleted instead, my verification fails as it detects onStart has been called instead which I am finding rather confusing.

I have tried using the ReplaySubject as such:

public void createOrderOnCompleteError() {
    orderOnCompleteSubject.onError(new Throwable("I am an error"));
}

public void createOrderOnCompleteSuccess() {
    orderOnCompleteSubject.onNext(new GenericResponse().setSuccess(true));
    orderOnCompleteSubject.onCompleted();
}

The error mechanism works fine.. the completed mechanism does not...