I am very new Jasmine unit test cases. My scenario may be easy but I am not sure how to cover test case for ngInit for below class. Can someone help me,
export class Component1 implements OnInit {
details$: Observable<any>;
name: string;
error: string
constructor(private service1: Service1, private service2: Service2) { }
ngOnInit() {
this.service1.service1Subject.subscribe( info => {
if(info['url']){
this.details$ = this.service2.get(info['url'])
this.details$.subscribe(
(info) => { this.name = info['name']};
(error) => { this.erro = error['error']};
);
}
});
}
}
Test case:
describe('Component1', () => {
let component: Component1;
let fixture: ComponentFixture<Component1>;
beforeEach(async(() => {
TestBed.configureTestingModule({
declarations: [Component1],
imports: [
HttpClientTestingModule, CommonModule
],
providers: [Service1, Service2]
})
.compileComponents();
}));
beforeEach(() => {
fixture = TestBed.createComponent(Component1);
component = fixture.componentInstance;
fixture.detectChanges();
});
it('should call Get Data', () => {
const service2: Service2 = TestBed.get(Service2);
const spy = jest.spyOn(service2, 'get').mockImplementation(() => {
return {
info : [...],
name : ''
}
});
component.ngOnInit();
expect(spy).toHaveBeenCalled();
});
});
The problem here is, I am not sure how to mock service1, RxJS subject. Please someone help me.
I see you're using Jest, but here's how I've set up component tests that use a service that expose a Subject
.
Perform your assertions
describe('Component1', () => { let component: Component1; let fixture: ComponentFixture<Component1>; //create mock service objects let service1Mock = jasmine.createSpyObj('service1', ['toString']); let service2Mock = jasmine.createSpyObj('service2', ['get']); beforeEach(async(() => { TestBed.configureTestingModule({ declarations: [Component1], imports: [ HttpClientTestingModule, CommonModule ], providers: [ //Set up the dependency injector, but use the mocks as the implementation { provide: Service1, useValue: service1Mock }, { provide: Service2, useValue: service2Mock } ] }).compileComponents(); })); beforeEach(() => { //add an observable to your service //this will also help reset the observable between each test service1Mock.service1Subject = new Subject<any>(); }); beforeEach(() => { fixture = TestBed.createComponent(Component1); component = fixture.componentInstance; fixture.detectChanges(); }); it('should get the data', () => { //configure the mock implementation of "service2.get" to successfully return data //You can alternatively use "throw({error: 'some_error'})" to test your "error" case service2Mock.get.and.returnValue(of({name: 'some_name'})); //tell the mock to emit some data! service1Mock.service1Subject.next( {url: 'some_url'} ); //Your component subcriptions should handle the event, perform whatever test needs to do }); });
I know that Jasmine was planning on making it possible to create spy objects with attributes , but I haven't actually used it myself.
As an aside, if you're not using details$
in your template, you can eliminate the variable entirely.
ngOnInit(){
this.service1.service1Subject.subscribe( info => {
if(info['url']){
this.service2.get(info['url']).subscribe(
(info) => { this.name = info['name']};
(error) => { this.error = error['error']};
);
}
});
}
Mock the subject first and then add it to mocked service.
describe('Component1', () => {
let component: Component1;
let fixture: ComponentFixture<Component1>;
let mockSubject = new Subject<boolean>();
mockSubject.next(true);
let mockService = jasmine.createSpyObj(Service, ['getTheme']);
beforeEach(async () => {
await TestBed.configureTestingModule({
declarations: [Component1],
providers: [{ provide: Service, useValue: mockService }],
}).compileComponents();
mockService.getTheme.and.returnValue(false);
mockService.theme$ = mockSubject; <---- assign mocked value
fixture = TestBed.createComponent(Component1);
component = fixture.componentInstance;
fixture.detectChanges();
});
})
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