There are a lot of different approaches to unit test your angular application you can find at the moment. A lot are already outdated and basically there's no real documentation at this point. So im really not sure which approach to use.
It seems a good approach at the moment is to use TestComponentBuilder, but i have some trouble to test parts of my code especially if a function on my component uses an injected service which returns an observable.
For example a basic Login Component with a Authentication Service (which uses a BackendService for the requests).
I leave out the templates here, because i don't want to test them with UnitTests (as far as i understood, TestComponentBuilder is pretty useful for this, but i just want to use a common approach for all my unit tests, and the it seems that TestComponentBuilder is supposed to handle every testable aspect, please correct me if i'm wrong here)
So i got my LoginComponent:
export class LoginComponent {
user:User;
isLoggingIn:boolean;
errorMessage:string;
username:string;
password:string;
constructor(private _authService:AuthService, private _router:Router) {
this._authService.isLoggedIn().subscribe(isLoggedIn => {
if(isLoggedIn) {
this._router.navigateByUrl('/anotherView');
}
});
}
login():any {
this.errorMessage = null;
this.isLoggingIn = true;
this._authService.login(this.username, this.password)
.subscribe(
user => {
this.user = user;
setTimeout(() => {
this._router.navigateByUrl('/anotherView');
}, 2000);
},
errorMessage => {
this.password = '';
this.errorMessage = errorMessage;
this.isLoggingIn = false;
}
);
}
}
My AuthService:
@Injectable()
export class AuthService {
private _user:User;
private _urls:any = {
...
};
constructor( private _backendService:BackendService,
@Inject(APP_CONFIG) private _config:Config,
private _localStorage:LocalstorageService,
private _router:Router) {
this._user = _localStorage.get(LOCALSTORAGE_KEYS.CURRENT_USER);
}
get user():User {
return this._user || this._localStorage.get(LOCALSTORAGE_KEYS.CURRENT_USER);
}
set user(user:User) {
this._user = user;
if (user) {
this._localStorage.set(LOCALSTORAGE_KEYS.CURRENT_USER, user);
} else {
this._localStorage.remove(LOCALSTORAGE_KEYS.CURRENT_USER);
}
}
isLoggedIn (): Observable<boolean> {
return this._backendService.get(this._config.apiUrl + this._urls.isLoggedIn)
.map(response => {
return !(!response || !response.IsUserAuthenticated);
});
}
login (username:string, password:string): Observable<User> {
let body = JSON.stringify({username, password});
return this._backendService.post(this._config.apiUrl + this._urls.login, body)
.map(() => {
this.user = new User(username);
return this.user;
});
}
logout ():Observable<any> {
return this._backendService.get(this._config.apiUrl + this._urls.logout)
.map(() => {
this.user = null;
this._router.navigateByUrl('/login');
return true;
});
}
}
and finally my BackendService:
@Injectable()
export class BackendService {
_lastErrorCode:number;
private _errorCodes = {
...
};
constructor( private _http:Http, private _router:Router) {
}
post(url:string, body:any):Observable<any> {
let options = new RequestOptions();
this._lastErrorCode = 0;
return this._http.post(url, body, options)
.map((response:any) => {
...
return body.Data;
})
.catch(this._handleError);
}
...
private _handleError(error:any) {
...
let errMsg = error.message || 'Server error';
return Observable.throw(errMsg);
}
}
Now i want to test the basic logic of logging in, one time it should fail and i expect an error message (which is thrown by my BackendService in its handleError function) and in another test it should login and set my User-object
This is my current approach for my Login.component.spec:
Updated: added fakeAsync like suggested in Günters answer.
export function main() {
describe('Login', () => {
beforeEachProviders(() => [
ROUTER_FAKE_PROVIDERS
]);
it('should try and fail logging in',
inject([TestComponentBuilder], fakeAsync((tcb: TestComponentBuilder) => {
tcb.createAsync(TestComponent)
.then((fixture: any) => {
tick();
fixture.detectChanges();
let loginInstance = fixture.debugElement.children[0].componentInstance;
expect(loginInstance.errorMessage).toBeUndefined();
loginInstance.login();
tick();
fixture.detectChanges();
expect(loginInstance.isLoggingIn).toBe(true);
fixture.detectChanges();
expect(loginInstance.isLoggingIn).toBe(false);
expect(loginInstance.errorMessage.length).toBeGreaterThan(0);
});
})));
it('should log in',
inject([TestComponentBuilder], fakeAsync((tcb: TestComponentBuilder) => {
tcb.createAsync(TestComponent)
.then((fixture: any) => {
tick();
fixture.detectChanges();
let loginInstance = fixture.debugElement.children[0].componentInstance;
loginInstance.username = 'abc';
loginInstance.password = '123';
loginInstance.login();
tick();
fixture.detectChanges();
expect(loginInstance.isLoggingIn).toBe(true);
expect(loginInstance.user).toEqual(jasmine.any(User));
});
})));
});
}
@Component({
selector: 'test-cmp',
template: `<my-login></my-login>`,
directives: [LoginComponent],
providers: [
HTTP_PROVIDERS,
provide(APP_CONFIG, {useValue: CONFIG}),
LocalstorageService,
BackendService,
AuthService,
BaseRequestOptions,
MockBackend,
provide(Http, {
useFactory: function(backend:ConnectionBackend, defaultOptions:BaseRequestOptions) {
return new Http(backend, defaultOptions);
},
deps: [MockBackend, BaseRequestOptions]
})
]
})
class TestComponent {
}
There are several issues with this test.
ERROR: 'Unhandled Promise rejection:', 'Cannot read property 'length' of null'I get this for the test of `loginInstance.errorMessage.lengthExpected true to be false.in the first test after i calledloginExpected undefined to equal <jasmine.any(User)>.in the second test after it should have logged in.
Any hints how to solve this? Am i using a wrong approach here? Any help would be really appreciated (and im sorry for the wall of text / code ;) )
