Trying to mock service property value

Question

I'd like to mock the value of a service property my component uses. I can't seem to get the value to change however.

The problem I'm having is getting the component to use my new value. It's still using the 'https://stackoverflow.com' value from my service.

Component

    import { ConfigService } from 'src/app/services/config/config.service';

    @Component({
      selector: 'app-some',
      templateUrl: './some.component.html',
      styleUrls: ['./some.component.scss'],
    })
    export class SomeComponent implements OnInit {
    
      newURL: string;
    
      constructor() {}
    
      ngOnInit() {
       ...
      }
    
      changeURL() {
        this.newURL = ConfigService.URL;
      }
    }

Service

    @Injectable({
      providedIn: 'root',
    })
    export class ConfigService {
      public static URL = 'https://stackoverflow.com';
    }

Spec

    describe('SomeComponent', () => {
      let component: SomeComponent;
      let fixture: ComponentFixture<SomeComponent>;
    
      const configServiceSpy = jasmine.createSpyObj(ConfigService, ['VERSION']);
    
      beforeEach(
        waitForAsync(() => {
          TestBed.configureTestingModule({
            imports: [HttpClientTestingModule, LoggerTestingModule, IonicModule],
            declarations: [SomeComponent],
          }).compileComponents();
        })
      );
    
      beforeEach(() => {
        fixture = TestBed.createComponent(SomeComponent);
        component = fixture.componentInstance;
        fixture.detectChanges();
      });
    
      it('should check if update is available', () => {
        component.changeURL();
        expect(component.newURL).toEqual('https://stackoverflow.com');
        // Now I'd like to mock this service property
        configServiceSpy.URL = 'https://google.com';
        component.changeURL();
        expect(component.newURL).toEqual('https://google.com');
      });
    });

Answer 1

Why don't you change it directly?

let backup = '';
beforeEach(() => backup = ConfigService.URL);
afterEach(() => ConfigService.URL = backup);

// ...

it('should check if update is available', () => {
  // ...
  ConfigService.URL = 'https://google.com';
  // ...
});