How to access private service which is provided by the component itself for unit testing

Question

I have this component which provides a service by itself

@Component({
    selector: 'my-component',
    providers: [MyService],
    ...
})
export class MyComponent { 
  constructor(@Self() private service: MyService) {}
  ...
}

During unit testing I noticed the following

beforeEach(() => {
    TestBed.configureTestingModule({
        declarations: [MyComponent],
        providers: [MyService],
    }).compileComponents();
    service = TestBed.inject(MyService);
});

That service is not the same instance as the service inside my component. I guess this makes sense, but I cannot find a solution for this, because for my tests I need access to that service inside my component. Any suggestions?

Answer 1

As mentioned in the comments above by @johnrsharpe its implementation detail so you shouldn't have to deal with it. Which is what I did, but I just found a way to do it. I don't need it anymore, but just for educational purposes I'll show it anyway:

let myService: MyService;

beforeEach(() => {
    myService = { ... };

    TestBed.configureTestingModule({
        declarations: [MyComponent],
        providers: [MyService],
    }).overrideComponent(MyComponent, {
        set: {
            providers: [
                provide: MyService, useValue: myService
            ]
        }
    });
}).compileComponents();

Now you can use myService for mocking and spying!