我如何用if，chai编写使用mocha

Question

我使用此演示来学习如何使用mocha

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/new.target

这是我的代码，（没有错误）

// JavaScript source code

var should = require('should');
var chai = require('chai');
var expect = require('chai').expect;
var assert = require('chai').assert;

describe('new.target', function () {

    describe('new.target in function calls', function () {

        function Foo() {
            if (!new.target) throw 'Foo() must be called with new';
        }

        it('Foo instantiated with new', function () {
            (new Foo()).should.be.an.instanceof(Foo);
        });

        it('Foo() must be called with new', function () {
            //Foo().should.throw('Foo() must be called with new');
            assert.throws(Foo, 'Foo() must be called with new');
        });

    });

});

但 Foo().should.throw('Foo() must be called with new');总是失败 并且Foo().should.throw(/Foo\(\) must be called with new/);也失败了

或者我应该不使用should？

https://github.com/tj/should.js#throw-and-throwerror

如何在不添加此代码的情况下执行此操作？并添加到npm test

var should = require('should');
var chai = require('chai');
var expect = require('chai').expect;
var assert = require('chai').assert;