Unit-Test et HttpClient

Pour "mocker" les appels HTTP, pas besoin d'utiliser les "spies" sur les méthodes de la classe HttpClient.

Le module HttpClientTestingModule fournit les services nécessaires pour contrôler les échanges HTTP.

describe('PickWeatherStation', () => {

    let httpTestingController: HttpTestingController;

    beforeEach(async(() => {
        TestBed.configureTestingModule({
          imports: [ HttpClientTestingModule ]
        })
            .compileComponents();
    }));
    
    let weatherStation: PickyWeatherStation;
    beforeEach(() => weatherStation = TestBed.get(PickyWeatherStation));

    let httpTestingController: HttpTestingController;
    beforeEach(() => httpTestingController = TestBed.get(HttpTestingController));
    
    afterEach(() => {
        httpTestingController.verify();
    });
    
    it('should get temperature from API', fakeAsync(() => {
    
        let temperature: number;

        weatherStation.getTemperature('Lyon')
            .subscribe(_temperature => temperature = _temperature);

        const req = httpTestingController.expectOne('/city-weather/lyon');

        req.flush({
            temperature: 30
        });

        expect(temperature).toEqual(30);
    
    }));
    
});

Pensez à toujours ajouter l'afterEach ci-dessous afin de vérifier qu'il n'y a aucune requête en attente !

afterEach(() => {
    httpTestingController.verify();
});