如何对需要其他模块的Node.js模块进行单元测试，以及如何模拟全局require函数?

这是一个简单的示例，它说明了我的问题的症结所在:

This is a trivial example that illustrates the crux of my problem:

var innerLib = require('./path/to/innerLib');

function underTest() {
    return innerLib.doComplexStuff();
}

module.exports = underTest;

我正在尝试为此代码编写单元测试.如何在不完全模拟require函数的情况下模拟对innerLib的需求?

I am trying to write a unit test for this code. How can I mock out the requirement for the innerLib without mocking out the require function entirely?

所以这是我试图模拟全局require并发现即使这样做也不起作用:

So this is me trying to mock out the global require and finding out that it won’t work even to do that:

var path = require('path'),
    vm = require('vm'),
    fs = require('fs'),
    indexPath = path.join(__dirname, './underTest');

var globalRequire = require;

require = function(name) {
    console.log('require: ' + name);
    switch(name) {
        case 'connect':
        case indexPath:
            return globalRequire(name);
            break;
    }
};

问题是underTest.js文件中的require函数实际上尚未被模拟.它仍然指向全局require函数.因此，似乎只能模拟正在执行模拟的同一文件中的require函数.如果我使用全局require来包含任何内容，即使在覆盖本地副本之后，这些文件仍然需要全局require引用.

The problem is that the require function inside the underTest.js file has actually not been mocked out. It still points to the global require function. So it seems that I can only mock out the require function within the same file I’m doing the mocking in. If I use the global require to include anything, even after I’ve overridden the local copy, the files being required will still have the global require reference.