Test Angular2 service with mock backend

Question

First: I\'m aware that Angular2 is in alpha and changing frequently.

I\'m working with Angular2. There is an injectable service with http dependency that I\

Answer 1

I just found this topic while looking for testing tips but I can't see a direct answer to that so...

This one is based on Angular RC.1

Testing service with Mock Backend

Let's say your service is:

import { Injectable } from '@angular/core';
import { Http } from '@angular/http';

@Injectable()
export class CoreService {
  constructor(private http: Http) {}

  getStatus() {
    return this.http.get('/api/status');
  }
}

Test to the service above will look like this:

import {
  beforeEach,
  beforeEachProviders,
  describe,
  expect,
  inject,
  it,
} from '@angular/core/testing';

import { provide } from '@angular/core';
import { BaseRequestOptions, Response, ResponseOptions } from '@angular/http';
import { MockBackend, MockConnection } from '@angular/http/testing';

describe('Http', () => {

  beforeEachProviders(() => [
    CoreService,
    BaseRequestOptions,
    MockBackend,
    provide(Http, {
      useFactory: (backend: MockBackend, defaultOptions: BaseRequestOptions) => {
        return new Http(backend, defaultOptions);
      },
      deps: [MockBackend, BaseRequestOptions]
    })
  ]);

  beforeEach(inject([MockBackend], (backend: MockBackend) => {
    const baseResponse = new Response(new ResponseOptions({ body: 'status' }));
    backend.connections.subscribe((c: MockConnection) => c.mockRespond(baseResponse));
  }));

  it('should return response when subscribed to getStatus',
    inject([CoreService], (coreService: CoreService) => {
      coreService.getStatus().subscribe((res: Response) => {
        expect(res.text()).toBe('status');
      });
    })
  );

})

What you really have to look at there is to have proper mocking in beforeEachProviders. Test itself is quite simple and ends up with subscribing to the service method.

---

Note: Don't forget to set base providers first:

import { setBaseTestProviders } from '@angular/core/testing';
import {
  TEST_BROWSER_DYNAMIC_APPLICATION_PROVIDERS,
  TEST_BROWSER_DYNAMIC_PLATFORM_PROVIDERS,
} from '@angular/platform-browser-dynamic/testing';

setBaseTestProviders(TEST_BROWSER_DYNAMIC_PLATFORM_PROVIDERS, TEST_BROWSER_DYNAMIC_APPLICATION_PROVIDERS);