http://stackoverflow.com/q/39472364/2587435

inject.spec.ts

import { Injectable } from '@angular/core';
import { async, inject, TestBed } from '@angular/core/testing';
import { MockBackend, MockConnection } from '@angular/http/testing';
import {
  Http, HttpModule, XHRBackend, ResponseOptions,
  Response, BaseRequestOptions
} from '@angular/http';

@Injectable()
class MetaManager {}

@Injectable()
class ApiConnectorService {
  constructor(private _http: Http) {}

  getHttp() {
    return this._http;
  }
}

@Injectable()
class EventDispatcher {}

@Injectable()
class ApiService {
  constructor(private _metaManager: MetaManager,
              private _connector: ApiConnectorService,
              private _dispatcher: EventDispatcher) {}

  getSomething(url) {
     return this._connector.getHttp().get(url).map(res => res.text());
  }

}

describe('service: ApiService', () => {
  beforeEach(() => {
    TestBed.configureTestingModule({
      providers: [
        {
          provide: Http, useFactory: (backend, options) => {
            return new Http(backend, options);
          },
          deps: [MockBackend, BaseRequestOptions]
        },
        MockBackend,
        BaseRequestOptions,
        MetaManager,
        ApiConnectorService,
        EventDispatcher,
        ApiService
      ]
    });
  });

  it('should get value',
    async(inject([ApiService, MockBackend],
                 (service: ApiService, backend: MockBackend) => {

    backend.connections.subscribe((conn: MockConnection) => {
      const options: ResponseOptions = new ResponseOptions({body: 'hello'});
      conn.mockRespond(new Response(options));
    });

    service.getSomething('http://dummy.com').subscribe(res => {
      console.log('subcription called');
      expect(res).toEqual('hello');
    });
  })));
});