Angular 5 dependency injection (service to test file)

Question

I am learning about marble tests and when following this tutorial I reached a point where my simple test looks like this:

user-effects.service.spec.ts

imports ...
describe('User Effects', () => {
    it('basic test', () => {
        const source = cold('--a', { a: { type: LOGIN } });
        const effects = new UserEffectsService(new Actions(source), ?? );

        const expected = cold('--b', { b: { type: LOGIN_SUCCESS } });
        expect(effects.login$).toBeObservable(expected);
    });
});

However my UserEffectsService needs 2 arguments

user-effects.service.ts

@Injectable()
export class UserEffectsService {
    constructor(private actions$: Actions, private userService: UserDataService) {
    }
    ...

Maybe I could pass there a new instance of UserDataService, but UserDataService needs 2 more arguments etc. and there would be a long chain. I couldn't find any solution for injecting a dependency without a constructor. Any tips how to deal with this case are appreciated, thanks.

@edit anyone? :D

Answer 1

There is a way to do this.

In your beforeEach you can inject services like this:

let service = TestBed.get(UserDataService)

then when you create new Effect Instance you can just pass instance of service.

const effectService = new UserEfectsService(action,service); 

If you have multiple services you can do something like this:

let [service1, service2, serviceN] = [Service1, Service2, ServiceN].map(TestBed.get);

Answer 2

Mock the injections into your service.

const actionsMock = {};
const userServiceMock = {};

Then, put all the variables and functions used in your current service, in your mocks.

For instance, let's say you use the getAllUsers function from your user service : then add it to your mock :

const userServiceMock = {
  getAllUsers: () => Observable.of([/* array of users */])
};

Now, you can create any number of objects you want :

const instance = new UserEffectsService(actionsMock, userServiceMock);