TestAppComponent.kt

@Component(
    modules = [
        AndroidSupportInjectionModule::class,
        FragmentContributorModule::class,
        DependencyModule::class
    ]
)
@AppScope
interface TestAppComponent {

    @Component.Builder
    interface TestBuilder {
        @BindsInstance
        fun app(app: Application): TestBuilder
        fun build(): TestAppComponent
    }

    fun inject(app: MainApplication)
}

@Module
abstract class FragmentContributorModule {
    @ContributesAndroidInjector
    abstract fun contributeMainFragment(): MainFragment
}