github_api.ts

import {Injectable} from 'angular2/core';
import {Http} from 'angular2/http';
import {Observable} from 'rxjs/Observable';
import 'rxjs/add/operator/map';

const GITHUB_API_URL = 'https://api.github.com';

export class Repository {
	name: string;
	full_name: string;
	stargazers_count: number;
	watchers_count: number;
	constructor({name, full_name, stargazers_count, watchers_count}) {
		this.name = name;
		this.full_name = full_name;
		this.stargazers_count = stargazers_count;
		this.watchers_count = watchers_count;
	}
}

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

	getRepo(org:string, name:string): Observable<Repository> {
		return this.http.get(`${GITHUB_API_URL}/repos/${org}/${name}`)
		  .map(res => res.json())
			.map(repoData => new Repository(repoData));
	}
}

github_api_spec.ts

import {GithubAPI, Repository} from './github_api';
import {Injector, provide} from 'angular2/core';
import {MockBackend, MockConnection} from 'angular2/http/testing';
import {HTTP_PROVIDERS, XHRBackend, Response, ResponseOptions} from 'angular2/http';

const ANGULAR_REPO_URL = 'https://api.github.com/repos/angular/angular';
const MOCK_API_RESPONSE = `
{
	"id": 24195339,
	"name": "angular",
	"full_name": "angular/angular",
	"stargazers_count": 2000,
	"watchers_count" : 1000
}`;

export function main() {
  describe('GithubAPI Service', () => {
		let injector:Injector;
		let backend:MockBackend;
		let githubAPI:GithubAPI;

    beforeEach(() => {
      injector = Injector.resolveAndCreate([
				HTTP_PROVIDERS,
				provide(XHRBackend, {useClass: MockBackend}),
				GithubAPI
			]);
			backend = injector.get(XHRBackend);
			githubAPI = injector.get(GithubAPI);
    });

    it('should instantiate the mock backend', () => {
      expect(githubAPI).toBeDefined();
    });

		it('should make a request to the Github API', (done) => {
			backend.connections.subscribe((c:MockConnection) => {
				expect(c.request.url).toEqual(ANGULAR_REPO_URL);
				done();
			});
			githubAPI.getRepo('angular', 'angular').subscribe();
    });

		it('should make a return an instance of a Repository', (done) => {
			backend.connections.subscribe((c:MockConnection) => {
				c.mockRespond(new Response(new ResponseOptions({body: MOCK_API_RESPONSE})));
			});
			githubAPI.getRepo('angular', 'angular').subscribe((repo:Repository) => {
				expect(repo instanceof Repository).toBe(true);
				expect(repo.full_name).toEqual('angular/angular');
				expect(repo.name).toEqual('angular');
				expect(repo.watchers_count).toEqual(1000);
				expect(repo.stargazers_count).toEqual(2000);
				done();
			});
    });
  });
}