How to test a fragment that depends on a dagger subcomponent?

Question

Note: I am not using Dagger-Android, just Dagger 2.

When I started writing my app I was injecting the fragment through the AppComponent so my integration test worked.

Then I created a subcomponent called MainComponent which lives in MainActivity. In my fragment I was getting the subcomponent using

((MainActivity) getActivity()).mainComponent.inject(this);

Then in my integration tests I would do

FragmentScenario.launchInContainer(RecipesListFragment.class, null, R.style.AppTheme, null)

which throws an error

EmptyFragmentActivity cannot be cast to ...MainActivity

as FragmentScenario launches the fragment in an EmptyFragmentActivity.

I thought that in order to fix this I could remove the dependency on MainActivity to get the component so I used a FragmentFactory and passed in MainComponent as a parameter. But now the test fails because when I create the FragmentScenario I do not have the MainComponent to pass it in the factory.

So is there a way to launch the scenario and still use the MainComponent subcomponent?

Answer 1

Posting what I did in the end to answer Henrique's question. I read a few posts about it but I can't find them now since it was some time ago.

There was no clear answer so I ended up using the dependency on MainActivity to inject since using the FragmentFactory proved too much hassle without many gains.

In the AndroidTest folder I created an empty MainTestActivity that extends MainActivity.

Then in the FragmentTest

ActivityScenario<MainTestActivity> scenario;

@Before
public void setUp() {
    scenario = ActivityScenario.launch(MainTestActivity.class).onActivity(activity -> {
        MainFragment fragment = new MainFragment();
        activity.startActivityFromFragment(fragment, new Intent(activity, MainTestActivity.class), 0);
    });
}