Angular 2 Services and Dependency Injection Testing a Service
Example
Given a service that can login a user:
import 'rxjs/add/operator/toPromise';
import { Http } from '@angular/http';
import { Injectable } from '@angular/core';
interface LoginCredentials {
password: string;
user: string;
}
@Injectable()
export class AuthService {
constructor(private http: Http) { }
async signIn({ user, password }: LoginCredentials) {
const response = await this.http.post('/login', {
password,
user,
}).toPromise();
return response.json();
}
}
It can be tested like this:
import { ConnectionBackend, Http, HttpModule, Response, ResponseOptions } from '@angular/http';
import { TestBed, async, inject } from '@angular/core/testing';
import { AuthService } from './auth.service';
import { MockBackend } from '@angular/http/testing';
import { MockConnection } from '@angular/http/testing';
describe('AuthService', () => {
beforeEach(() => {
TestBed.configureTestingModule({
imports: [HttpModule],
providers: [
AuthService,
Http,
{ provide: ConnectionBackend, useClass: MockBackend },
]
});
});
it('should be created', inject([AuthService], (service: AuthService) => {
expect(service).toBeTruthy();
}));
// Alternative 1
it('should login user if right credentials are passed', async(
inject([AuthService], async (authService) => {
const backend: MockBackend = TestBed.get(ConnectionBackend);
const http: Http = TestBed.get(Http);
backend.connections.subscribe((c: MockConnection) => {
c.mockRespond(
new Response(
new ResponseOptions({
body: {
accessToken: 'abcdef',
},
}),
),
);
});
const result = await authService.signIn({ password: 'ok', user: 'bruno' });
expect(result).toEqual({
accessToken: 'abcdef',
});
}))
);
// Alternative 2
it('should login user if right credentials are passed', async () => {
const backend: MockBackend = TestBed.get(ConnectionBackend);
const http: Http = TestBed.get(Http);
backend.connections.subscribe((c: MockConnection) => {
c.mockRespond(
new Response(
new ResponseOptions({
body: {
accessToken: 'abcdef',
},
}),
),
);
});
const authService: AuthService = TestBed.get(AuthService);
const result = await authService.signIn({ password: 'ok', user: 'bruno' });
expect(result).toEqual({
accessToken: 'abcdef',
});
});
// Alternative 3
it('should login user if right credentials are passed', async (done) => {
const authService: AuthService = TestBed.get(AuthService);
const backend: MockBackend = TestBed.get(ConnectionBackend);
const http: Http = TestBed.get(Http);
backend.connections.subscribe((c: MockConnection) => {
c.mockRespond(
new Response(
new ResponseOptions({
body: {
accessToken: 'abcdef',
},
}),
),
);
});
try {
const result = await authService.signIn({ password: 'ok', user: 'bruno' });
expect(result).toEqual({
accessToken: 'abcdef',
});
done();
} catch (err) {
fail(err);
done();
}
});
});
