角度单元测试 - 注入失败[重复]

Question

我正在尝试创建一个 Angular 单元测试，但马上就失败了。

我已经查看了this 和 this 这个 SO，这似乎正是我正在努力解决的问题，但在尝试了那里提到的修复后，我仍然不正确。

这是我的代码：

import { TestBed } from '@angular/core/testing';

import { ContactsService } from './contacts.service';
import { HttpClientTestingModule } from '@angular/common/http/testing';
import { HttpClient } from '@angular/common/http';

describe('ContactsService', () => {


   beforeEach(() => {
     TestBed.configureTestingModule({
       imports: [ HttpClientTestingModule, ContactsService, HttpClient],
  })
  .compileComponents();
  });


});

当我运行一个 ng 测试时，我得到了这个错误：

NullInjectorError: R3InjectorError(DynamicTestModule)[ContactsService -> HttpClient -> HttpClient]: NullInjectorError: 没有 HttpClient 的提供者！

我的 .ts，为了完整性：

import { Injectable } from '@angular/core';
import { HttpClient, HttpHeaders } from '@angular/common/http';
import { Entry } from '../classes/entry';
import { EntrySearch } from '../classes/entrySearch';

@Injectable({
  providedIn: 'root'
})
export class ContactsService {

  constructor(private http: HttpClient) { }

}

Answer 1

是的，就像 tilo 所说，它应该有效。 并尝试让你的beforeEach - async()。

试试这个 - 稍微修改一下（参见声明部分）：

import { TestBed } from '@angular/core/testing';

import { ContactsService } from './contacts.service';
import { HttpClientTestingModule } from '@angular/common/http/testing';

describe('ContactsService', () => {


   beforeEach(async(() => {
     TestBed.configureTestingModule({
       declarations: [ContactsService],
       imports: [ HttpClientTestingModule]
  })
  .compileComponents();
  }));


});

Answer 2

您只需要导入HttpClientTestingModule 并提供您的ContactsService：

import { ContactsService } from './contacts.service';
import { HttpClientTestingModule } from '@angular/common/http/testing';
import { TestBed } from '@angular/core/testing';

describe('ContactsService', () => {
  beforeEach(() => TestBed.configureTestingModule({
    imports: [ HttpClientTestingModule ],
    providers: [ ContactsService ]
  }));

 it('should be created', () => {
    const service: ContactsService = TestBed.inject(ContactsService);
    expect(service).toBeTruthy();
   });
});