无法编写测试案例以引发新的InternalServerErrorException

Question

我正在编写一个测试用例，当提供的响应未定义时应该抛出错误。但是我得到这个错误

 if (isObjectUndefinedOrEmpty(res) && isObjectUndefinedOrEmpty(res2)) {
    > 5 |         throw new InternalServerErrorException(
        |               ^
      6 |             'Requests to get content failed!'
      7 |         );
      8 |     }

PFB代码和我的规格文件。

// spec file

  it('should return an error if isObjectUndefinedOrEmpty returns an undefined or empty object', () => {

    const res=
    undefined
    expect( ()=> {
      handleRequestsFailed(res) 
     }).toThrow(new InternalServerErrorException('Requests to get content failed!'));
  });

// ts file

export function handleRequestsFailed(res, res2?: any) {
    if (isObjectUndefinedOrEmpty(res) && isObjectUndefinedOrEmpty(res2)) {
        throw new InternalServerErrorException(
            'Requests to get content failed!'
        );
    }
}

export function isObjectUndefinedOrEmpty(obj: any) {
    return !obj || Object.keys(obj).length === 0;
}