ActivityScenario: Custom instanciation

[saschpe]

Description

The launch(Activity) method can't be customized very well, especially compared to launchFragmentInContainer / FragmentScenario. That makes it particularly hard to test / verify code that happens during onCreate(). In our example, a MainActivity (that contains the NavHostFragment for Jetpack Navigation) navigates to an on-boarding screen on first start.
Verifying this code is hard with the current ActivityScenario as the initial state can't be controlled and thus we can't properly mock / spy the navigation controller (Compared to how it can be done with FragmentScenario).

Expected Results

Ideally, launch(Activity) take a custom ActivityFactory or Lambda like launchFragmentInContainer that allows to customize activity creation. A convenience parameter to decide which state to launch into (i.e. CREATED, RESUMED) won't hurt either.

Link to a public git repo demonstrating the problem:

See https://issuetracker.google.com/issues/139695101

Versions

testImplementation("androidx.arch.core:core-testing:2.0.1")
testImplementation("androidx.test.espresso:espresso-core:3.2.0")
testImplementation("androidx.test.ext:junit-ktx:1.1.1")
testImplementation("io.mockk:mockk:1.9.3")
testImplementation("org.robolectric:robolectric:4.3")

[sebokopter]

I want to second @saschpe : Having a custom/intercepting Activity factory allows for providing test instances via a constructor instead of exposing a public setter only for testing.

ActivityTestRule has a constructor with an SingleActivityFactory interface:

ActivityTestRule(SingleActivityFactory<T> activityFactory, boolean initialTouchMode, boolean launchActivity)

Since ActivityTestRule is marked deprecated are there any plans to (re-)introduce this behavior to ActivityScenarionRule? Or would you at least welcome a PR?