class ComicApplication : MultiDexApplication() {

    val component =
        DaggerApplicationComponent.builder()
            .testModule(TestModule())
            .applicationModule(ApplicationModule(this))
            .databaseModule(DatabaseModule())
            .build()


    @Inject lateinit var file: DbFile

    override fun onCreate() {
        super.onCreate()
        component.inject(this)
        Toast.makeText(this, "Test ${file.path}", Toast.LENGTH_LONG).show()
    }

}

class MainActivity : AppCompatActivity() {

    @Inject lateinit var file: DbFile

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        Toast.makeText(this, "Test ${file.path}", Toast.LENGTH_LONG).show()
...
}
}

@Component(modules = [ApplicationModule::class, DatabaseModule::class, TestModule::class])
@Singleton
interface ApplicationComponent {
    fun inject(comicApplication: ComicApplication)
    fun dbFile() : DbFile
    fun database() : ComicDatabase
}

@Module
class TestModule {

    @Provides
    fun file(): DbFile = DbFile(0,"123",0,0,0,0,"zzz")

}