Mock Activity Injector

MockActivityInjector.kt

@RunWith(AndroidJUnit4::class)
class MainViewTests {
  val mockUserAction = mock(MainContract.UserAction::class.java)

  @get:Rule
  val activityTestRule = object : ActivityTestRule<MainActivity>(MainActivity::class.java, true, true) {
    override fun beforeActivityLaunched() {
      super.beforeActivityLaunched()
      val myApp = InstrumentationRegistry.getTargetContext().applicationContext as MyApp
      myApp.dispatchingActivityInjector = createFakeFragmentInjector<MainFragment> {
        userAction = mockUserAction
        // mock only userAction and use the original otherMemberThatIDoNotWantToMock
        // otherMemberThatIDoNotWantToMock = ...
      }
    }
  }
}


inline fun <reified T : Activity> createFakeActivityInjector(crossinline block : T.() -> Unit)
    : DispatchingAndroidInjector<Activity> {
  val myApp = InstrumentationRegistry.getTargetContext().applicationContext as MyApp
  val originalDispatchingActivityInjector = myApp.dispatchingActivityInjector
  val injector = AndroidInjector<Activity> { instance ->
    originalDispatchingActivityInjector.inject(activity)
    if (instance is T) {
      instance.block()
    }
  }
  val factory = AndroidInjector.Factory<Activity> { injector }
  val map = mapOf(Pair<Class <out Activity>, Provider<Factory<out Activity>>>(T::class.java, Provider { factory }))
  return DispatchingAndroidInjector_Factory.newDispatchingAndroidInjector(map)
}