在测试套件上，我想用链接方法模拟模型findOne然后select

登录服务

public loggingIn = async (loginDTO: LoginDTO) => {
    const user = await UserModel.findOne({ email : loginDTO.email }).select(['_id', 'username', 'email', 'password']);
    if (user) {
      const isPasswordMatching = await bcrypt.compare(loginDTO.password, user.password);
      if (isPasswordMatching) {
        const token = this.generateToken(user);
        const tokenDTO : TokenDTO = {
          access_token: token,
          expiresIn: loginConstant.EXPIRES_IN,
        };
        return tokenDTO;
      }
      throw new InvalidCrendentialsException();
    }
    throw new InvalidCrendentialsException();
  }

测试

it('should return access_token when login is success', async () => {
      UserModel.findOne = jest.fn().mockResolvedValueOnce(UserFactory.successResponse);
      bcrypt.compare = …