MVI-sample unit tests for presenters

[hussam789]

I was wondering if you want to build this sample using TDD, and probably start writing tests for MviPresenters, but currently MviBasePresenter has bindIntents function which

Observable<PartialHomeViewState> allIntentsObservable =
        Observable.merge(loadFirstPage, nextPage, pullToRefresh, loadMoreFromGroup)
            .observeOn(AndroidSchedulers.mainThread());

subscribeViewState(allIntentsObservable.scan(initialState, this::viewStateReducer),
        HomeView::render);

But if you want to write to test the MviPresenter, you want to test each Intent function e.g (loadFirstPage, pullToRefresh...). based on MVI pattern, given previousState (ViewModel) the Presenter applies the Model function (for example loadFirstPage) and uses StateReducer function to output a newState

[sockeqwe]

1. In a real world app you wouldn't put all that things into your Presenter but rather in a HomeFeedInteractor which handles all those intents and applies the stateReducer. Maybe we should refactor that.
2. I'm sorry, but I don't understand what exactly your question is / the purpose of this issue.

[hussam789]

I understand, my question is could you provide an example for a unit test for the presenter in MVI sample app (currently there are no tests for it)? Or can you give us any advice for writing a test for MVI pattern in general?

[sockeqwe]

Got it! Yes that is not documented at all. I apologise. I will write add some unit tests for the sample app and will beginn to write documentation / github pages for MVI and Testing.

Basically, to test a MVI presenter you have to do the following: 1) Create a View Instance i.e. by using Mockito 2) Instantiate your presenter 3) call presenter.attachView(yourMockedView). This calls internally presenter.bindIntents() 4) now your presenter is setup properly and bound to the view. Now you can invoke the intent you want to test. 5) invoking an intent will finally result in a view.render(model). Then you catch this model and test it like Assert.assertEquals(expectedModel, receivedModel)

hussam789 notifications@github.com schrieb am Do., 26. Jan. 2017, 22:35:

I understand, my question is could you provide an example for a unit test for the presenter in MVI sample app (currently there are no tests for it)? Or can you give us any advice for writing a test for MVI pattern in general?

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[sockeqwe]

Full example can be found here: https://github.com/sockeqwe/mosby/blob/master/sample-mvi/src/test/java/com/hannesdorfmann/mosby3/sample/mvi/view/home/HomePresenterTest.java

Will also put more infos about testing in documentation