How to apply Dagger injection into services?

Fragment & Activity injection is done through registerActivityLifecycleCallbacks and registerFragmentLifecycleCallbacks, but it’s unclear how to turn on injection for Services. Any ideas?

[Nauce]

Here’s my solution:

Make Application implements HasServiceInjector and inject a DispatchingAndroidInjector for services.

public class App extends Application implements HasActivityInjector, HasServiceInjector {

    @Inject
    DispatchingAndroidInjector<Activity> dispatchingActivityInjector;
    @Inject
    DispatchingAndroidInjector<Service> dispatchingServiceInjector;

    @Override
    public void onCreate() {
        super.onCreate();
        AppInjector.init(this);
    }

    @Override
    public AndroidInjector<Activity> activityInjector() {
        return dispatchingActivityInjector;
    }

    @Override
    public AndroidInjector<Service> serviceInjector() {
        return dispatchingServiceInjector;
    }

}

Create a new module to perform injection over your services.

@Module
abstract class ServiceBuilderModule {

    @ContributesAndroidInjector
    abstract MyService contributeMyService();

}

Register your new module in your application’s component.

@Component(modules = {
        AndroidSupportInjectionModule.class,
        AppModule.class,
        ActivityBuilderModule.class,
        ServiceBuilderModule.class
})
@Singleton
public interface AppComponent {

    @Component.Builder
    interface Builder {
        @BindsInstance
        Builder application(App application);

        AppComponent build();
    }

    void inject(App app);

}

And finally, override method onCreate of the service adding AndroidInjection.inject(this).

public class MyService extends Service {

    @Override
    public void onCreate() {
        AndroidInjection.inject(this);
        super.onCreate();
    }

    @Nullable
    @Override
    public IBinder onBind(Intent intent) {
        return null;
    }
    
}

[pzmudzinski]

Ok, but what about integration tests? It will crash since Github example app is using different Application class which disables Dagger initialization and you are responsible for manually providing mock-objects into properties.