Question

我运行ng test命令时显示的错误。

这是我的服务规范，

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

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

）; }）;

BackendService.ts看起来像，

export class BackendService {
  private baseUrl: string = 'https://foo-backend.appspot.com/_ah/api/default/v1';

  constructor(private http: Http, baseName: string) {
    this.baseUrl = this.baseUrl + baseName;
  }
  .....
}

似乎BackendService类的构造函数中的额外参数会导致此问题..

Answer 1

你如何期望Angular知道baseName应该是什么？所有构造函数参数都需要从Injector获取。如果参数没有相应的标记，则无法查找它。

您可以通过执行

添加令牌

// somewhere in some file
import { OpaqueToken } from '@angular/core';

export const BASE_NAME_TOKEN = new OpaqueToken("app.base_name");

// in test class
import { BASE_NAME_TOKEN } from 'where-ever'

TestBed.configureTestingModule({
  providers: [
    BackendService,
    { provide: BASE_NAME_TOKEN, useValue: 'whatever-the-base-is' }
  ]
});

// in service constructor
import { Inject } from '@angular/core'
import { BASE_NAME_TOKEN } from 'where-ever'

constructor(http: Http, @Inject(BASE_NAME_TOKEN) baseName: string) {}

另见：

`ng test`显示错误：无法解析BackendService的所有参数

1 个答案: