如何测试这个 Angular 2 服务？答案

【问题标题】：How can I test this Angular 2 service?如何测试这个 Angular 2 服务？
【发布时间】：2016-07-20 14:16:13
【问题描述】：

我的 Angular 应用程序中有以下服务：

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

@Injectable()
export class BookService {

  constructor(private http: Http) {}

  getList() {
    return this.http.get('/api/books.json');
  }
}

如何测试getList() 函数？

我不需要每一个细节，只需要一些大方向。我认为这是相当陈旧的领域，但我很难找到关于人们通常如何进行此类测试的文档。一旦我知道了前进的方向，我可能可以自己追查细节。

【问题讨论】：

标签： testing typescript angular

【解决方案1】：

import {addProviders, inject} from '@angular/core/testing';

describe('my code', () => {
  beforeEach(() => {
    addProviders([
      BookService, 
      HTTP_PROVIDERS,
      MockBackend,
      {provide: XHRBackend, useExiting: MockBackend}]);
  });

  it('does stuff', inject([BookService], (service) => {
    // actual test
  });
});

【讨论】：

感谢您的回答。我认为这有助于阐明这个主题，尽管我对it 的内部的内容更感兴趣:)。我创建了一个单独的问题来描述我目前正在尝试的内容。也许一旦解决了这个问题，我们就可以将解决方案拼接到这个答案中。 stackoverflow.com/questions/38484765/…

【解决方案2】：

我自己又搞砸了一些。以下是我为测试本身提出的建议：

  it('should assign a list of books', inject([BookService, MockBackend, Http], (bookService, backend, http) => {
    backend.connections.subscribe(connection => {
      var mockResponse = new Response(new ResponseOptions({
        body: [{ name: 'Whiteboard Interviews' }]
      }));
      connection.mockRespond(mockResponse);
    });

    let service = new BookService(http);
    service.getList().subscribe(response => {
      expect(response.json()).toEqual([{ name: 'Whiteboard Interviews' }]);
    });
  }));

这是完整的规范文件：

/* tslint:disable:no-unused-variable */

import { provide } from '@angular/core';
import { MockBackend } from '@angular/http/testing';

import {
  Http,
  HTTP_PROVIDERS,
  Response,
  ResponseOptions,
  BaseRequestOptions,
  ConnectionBackend
} from '@angular/http';

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

import { BookService } from './book.service';

describe('Book Service', () => {
  beforeEachProviders(() => [
    BookService,
    HTTP_PROVIDERS,
    MockBackend,
    BaseRequestOptions,
    provide(Http, {
      useFactory: function (backend:ConnectionBackend, defaultOptions:BaseRequestOptions) {
        return new Http(backend, defaultOptions);
      },
      deps: [MockBackend, BaseRequestOptions]
    })
  ]);

  it('should ...',
      inject([BookService], (service: BookService) => {
    expect(service).toBeTruthy();
  }));

  it('should assign a list of books', inject([BookService, MockBackend, Http], (bookService, backend, http) => {
    backend.connections.subscribe(connection => {
      var mockResponse = new Response(new ResponseOptions({
        body: [{ name: 'Whiteboard Interviews' }]
      }));
      connection.mockRespond(mockResponse);
    });

    let service = new BookService(http);
    service.getList().subscribe(response => {
      expect(response.json()).toEqual([{ name: 'Whiteboard Interviews' }]);
    });
  }));
});

【讨论】：