Application class - https://android.jlelse.eu/instrumentation-testing-with-dagger2-retrofit2-mockwebserver-android-4cca7cb7373c

AppDelegate.kt

open class GitHubDelegate : Application() {
  
    open lateinit var appDaggerComponent: GitHubAppComponent

    override fun onCreate() {
        super.onCreate()
        appDaggerComponent = getAppComponent()
        appDaggerComponent.inject(this)
    }

    //  returns app component
    open fun getAppComponent(): GitHubAppComponent =
        DaggerGitHubAppComponent
            .builder()
            .applicationModule(ApplicationModule(this))
            .build()
}