Testing Fragments that depend on a Activity.

onFragment.kt

abstract val destination: Int

    inline fun <reified F : Fragment> onFragment(crossinline block: F.() -> Unit) {
        val intent = Intent(
            ApplicationProvider.getApplicationContext<Application>(),
            MainActivity::class.java
        ).apply { flags = Intent.FLAG_ACTIVITY_NEW_TASK }
        val scenario = ActivityScenario.launch<MainActivity>(intent)
        scenario.onActivity {
            Shadows.shadowOf(Looper.getMainLooper()).idle()
            val navController = mock<NavController>()
            ShadowNavigation.setNavController(navController)
            ShadowNavHostFragment.setNavController(navController)

            val fragment = it
                .supportFragmentManager
                .fragments
                .first()
                .childFragmentManager
                .fragments
                .first() as F

            block(fragment)
        }
        ShadowNavigation.resetNavController()
        scenario.close()

    }