无法为用户模型创建模拟构造函数

Question

当我试图模拟我的用户模型来测试我的服务时，nest 控制台抛出这个 TypeError，但我不知道 'emulate'用户模型的构造函数

user.service.spec.ts

import { Test, TestingModule } from '@nestjs/testing';
import { getModelToken } from '@nestjs/mongoose';
import { UserService } from './user.service';
import { User } from './interfaces/user.interface';

const mockUsersModel = {
  save: jest.fn().mockImplementation((user) => Promise.resolve({id: Date.now(), ...user}))
};

describe('UserService', () => {
  let service: UserService;

  beforeEach(async () => {
    const module: TestingModule = await Test.createTestingModule({
      providers: [UserService,
      {
        provide: getModelToken('User'),
        useValue: mockUsersModel
      }],
    }).compile();

    service = module.get<UserService>(UserService);
  });

  it('should be defined', () => {
    expect(service).toBeDefined();
  });

  it('should create a new user record and return it', async() => {
    expect(await service.createUser({email: 'user@user.com', password:'safe-password',
                                     online: true})).toEqual({
      id: expect.any(Number),
      email: 'user@user.com',
      password: 'safe-password'
    })
  })
});

user.serive.ts

constructor(@InjectModel('User') private readonly userModel: Model<User>){}

  async createUser(createUserDTO: CreateUserDTO): Promise<User>{
    const newUser = new this.userModel(createUserDTO);
    return newUser.save();
  }

Answer 1

new this.userModel 应为可实例化对象（具有构造函数并可用于实例化新对象实例的对象，如 class 或构造函数）。但是，您作为 @InjectModel('User') 装饰器的参数传递的 mockUsersModel 不是可实例化的对象。因此调用 new 会引发错误。

鉴于您的用例，最好通过将构造函数分配给 mockUsersModel 来解决此问题，如下所示：

const mockUsersModel = function() {
  save: jest.fn().mockImplementation((user) => Promise.resolve({id: Date.now(), ...user}))
};

无法为用户模型创建模拟构造函数

Can't create mock constructor for user model

javascript

node.js

typescript

jestjs

nestjs