Unit Test - Verify Observable is subscribed

Question

I have got the java code like this

 mDataManager.getObservable(\"hello\").subscribe( subscriber );

and I want to verify the follow

Answer 1

Maybe you could use Observable.onSubscribe method together with RunTestOnContext rule? The TestContext can provide you with an Async object, that terminates the test only once it is completed. I think, that if you combine this with Observable#doOnSubscribe you can achieve the desired behavior.

However, using Async might be a bit confusing sometimes. In the example below, if the observable is never subscribed onto, the doOnSubscribe function would never get evaluated and your test would not terminate.

Example:

@RunWith(VertxUnitRunner.class)
public class SubscriptionTest {

  @Rule
  public RunTestOnContext vertxRule = new RunTestOnContext();

  @Test
  public void observableMustBeSubscribed(final TestContext context) {
    final Async async = context.async();
    final Observable observable = Observable.just("hello").doOnSubscribe(async::complete);
    final Manager mock = mock(Manager.class);
    when(mock.getObservable()).thenReturn(observable);

    mock.getObservable().subscribe();
  }

  interface Manager {
    Observable getObservable();
  }
}