vfeedback.service.spec.ts

let snackSpy = jasmine.createSpyObj('snackBar', ['open']);

//...
//....beforeEach, TestBed configurations etc
//...

it('should let listeners subscribe', function () {
        expect(service._listeners.length).toBe(0);
        service.addListener({
            onLoading: () => {
            }, onLoadingComplete: () => {
            }
        });
        expect(service._listeners.length).toBe(1);
    });

    it('should remove listeners on removal', function () {
        expect(service._listeners.length).toBe(0);
        let listener = {
            onLoading: () => {
            }, onLoadingComplete: () => {
            }
        };
        service.addListener(listener);
        service.addListener(listener);
        service.addListener(listener);
        expect(service._listeners.length).toBe(3);
        service.removeListener(listener);
        expect(service._listeners.length).toBe(0);
    });

    it('should notify spinners of processing events and completion', fakeAsync(() => {

        let listenerSpy = jasmine.createSpyObj('listenerSpy', ['onLoading', 'onLoadingComplete']);
        service.addListener(listenerSpy);

        let obs = new Observable(subscribe => {
            subscribe.next('foobar');
            subscribe.complete();
        });
        service.spinUntilCompleted(obs);
        //wait one async cycle
        tick();
        expect(listenerSpy.onLoading).toHaveBeenCalledTimes(1);

        expect(listenerSpy.onLoadingComplete).toHaveBeenCalledTimes(1);

    }));

    it('should not notify spinners if observable has not been completed', fakeAsync(() => {
        let listenerSpy = jasmine.createSpyObj('listenerSpy', ['onLoading', 'onLoadingComplete']);
        service.addListener(listenerSpy);

        let obs = new Observable(subscribe => {
            subscribe.next('foobar');
        });
        service.spinUntilCompleted(obs);
        //wait one async cycle
        tick();
        expect(listenerSpy.onLoadingComplete).toHaveBeenCalledTimes(0);
    }));


    it('should call MdSnackBar on successful response from observable', done => {
        service.showMessageOnAnswer('hooray!', null, new Observable(sub => {
            sub.next('fake server response');
            sub.complete();
        }))
        //inside observable subscription of service
            .subscribe(next => {
                expect(snackSpy.open).toHaveBeenCalledWith('hooray!', undefined, {duration: 1500})
            }, null, done);
    });


    it('should call MdSnackBar  with error on failed response from observable', done => {
        service.showMessageOnAnswer('hooray!', 'fail :(', new Observable(sub => {
            sub.error();
            sub.complete();
        }))
        //inside observable subscription of service
            .subscribe(next => {
                expect(snackSpy.open).toHaveBeenCalledWith('fail :(', undefined, {duration: 1500});
            }, null, done);
    });