proxyquireify/lib/prelude.js

Proxies browserify's require in order to allow overriding dependencies during testing.

// modules are defined as an array
// [ module function, map of requireuires ]
//
// map of requireuires is short require name -> numeric require
//
// anything defined in a previous bundle is accessed via the
// orig method which is the requireuire for previous bundles

(function outer (modules, cache, entry) {
    // Save the require from previous bundle to this closure if any
    var previousRequire = typeof require == "function" && require;

    function findProxyquireifyName() {
        var deps = Object.keys(modules)
            .map(function (k) { return modules[k][1]; });

        for (var i = 0; i < deps.length; i++) {
            var pq = deps[i]['proxyquireify'];
            if (pq) return pq;
        }
    }

    var proxyquireifyName = findProxyquireifyName();

    function newRequire(name, jumped){
        // Find the proxyquireify module, if present
        var pqify = (proxyquireifyName != null) && cache[proxyquireifyName];

        // Proxyquireify provides a separate cache that is used when inside
        // a proxyquire call, and is set to null outside a proxyquire call.
        // This allows the regular caching semantics to work correctly both
        // inside and outside proxyquire calls while keeping the cached
        // modules isolated.
        // When switching from one proxyquire call to another, it clears
        // the cache to prevent contamination between different sets
        // of stubs.
        var currentCache = (pqify && pqify.exports._cache) || cache;

        if(!currentCache[name]) {
            if(!modules[name]) {
                // if we cannot find the the module within our internal map or
                // cache jump to the current global require ie. the last bundle
                // that was added to the page.
                var currentRequire = typeof require == "function" && require;
                if (!jumped && currentRequire) return currentRequire(name, true);

                // If there are other bundles on this page the require from the
                // previous one is saved to 'previousRequire'. Repeat this as
                // many times as there are bundles until the module is found or
                // we exhaust the require chain.
                if (previousRequire) return previousRequire(name, true);
                var err = new Error('Cannot find module \'' + name + '\'');
                err.code = 'MODULE_NOT_FOUND';
                throw err;
            }
            var m = currentCache[name] = {exports:{}};

            // The normal browserify require function
            var req = function(x){
                var id = modules[name][1][x];
                return newRequire(id ? id : x);
            };

            // The require function substituted for proxyquireify
            var moduleRequire = function(x){
                var pqify = (proxyquireifyName != null) && cache[proxyquireifyName];
                // Only try to use the proxyquireify version if it has been `require`d
                if (pqify && pqify.exports._proxy) {
                    return pqify.exports._proxy(req, x);
                } else {
                    return req(x);
                }
            };

            modules[name][0].call(m.exports,moduleRequire,m,m.exports,outer,modules,currentCache,entry);
        }
        return currentCache[name].exports;
    }
    for(var i=0;i<entry.length;i++) newRequire(entry[i]);

    // Override the current require with this new one
    return newRequire;
})