In dependent component mode, Dagger 2 uses only components. Here we have two of them, one for the whole application (ApplicationComponent), and one shared by all the activities (ActivityComponent).
There are three activities, Main has a button to open Detail that has a button to open Another. Dagger is using Scopes by means of the @PerActivity annotation, what means that every activity will have its own "context singletons" in addition to the app wide singletons.
In order to verify wich instances are injected in wich Scope, the Navigator class will log collaborator instances.
Two test classes are provided as samples. MainPresenterShould tests MainPresenter that is a pure java class with no Android dependencies. It is easy to test because all the required collaborators are injected by constructor.
NavigatorShould is a bit more complicated. As Navigator class relies on Android framework, we need to mock Android. We can do it running this class with Robolectric test runner.
AppCollaborator is injected as IAppCollaborator interface (Sorry for the old naming style) and have two versions, the one used in the app and the one for instrumentation tests. think on this collaborator as the Network API repository or whatever other class you must mock app level in your instrumentation tests.
Using a custom instrumentation runner and extending AndroidApplication and ApplicationComponent with test versions, we are able to substitute ApplicationModule (Or any other app level module) by the one that provides Mock version of the desired classes like AppCollaborator.
####1- Open tha app, navigate to detail, another and check the logs:
- Context and AppCollaborator share the same instance in Navigator logs, why?
- Activity and ActCollaborator are different instances in Navigator logs, why?
- ActCollaborator share the same instance between DetailPresenter and the second Navigator log, why?
####2- In ApplicationModule comment out the Singleton annotation from AppCollaborator and run again:
- AppCollaborator is no longer the same instance, why?
####3- In ApplicationModule set back the Singleton annotation to AppCollaborator. Now in ApplicationComponent comment out the AppColaborator provideAppCollaborator(); line and run again:
- AppCollaborator is no longer the same instance, why?