smart_commonjs_require.js

var require;
(function(){

    var module = {};
    require = function(module_name, stack){
        if(!stack) stack = [];
        var self = arguments.callee;

        var resolved = resolve(module_name, stack);
        var [use_string, breakup] = [resolved.identifier, resolved.breakup];

        if(self.moduleCache[use_string]) return self.moduleCache[use_string].exports;
        self.moduleCache[use_string] = { id: use_string, exports: {} };
        
        if(breakup.length > 1){
            try {
                system.filesystem.get(self.path + use_string + ".js");
            } catch (e) {
                // If relative file doesn't exist, fall back to absolute
                var resolved_again = resolve(breakup[breakup.length -1], stack);
                [use_string, breakup] = [resolved_again.identifier, resolved_again.breakup];
            }
        }

        var new_require = function(new_module_name){
            return require(new_module_name, stack.concat( breakup.slice(0, -1) ));
        };

        var func = load(use_string);
        func.apply(func, [new_require, module, self.moduleCache[use_string].exports]);
      
        return self.moduleCache[use_string].exports;
    };
    require.moduleCache = {};
    require.path = '';

    var resolve = function(module_name, stack) {
        var breakup = module_name.split('/');

        switch(breakup[0]){
            case '.':
                breakup.shift(); break;
            case '..':
                if(stack.length == 0) throw new Error("Unable to load module '"+module_name+"', already at top level");
                stack.pop(); breakup.shift(); break;
            default:
                stack = []; break;
        }         
        
        var [current_directory, relative_file] = [stack.join('/'), breakup.join('/')];
        var use_string = current_directory ? (current_directory + '/' + relative_file) : relative_file;
        return { 'identifier': use_string, 'breakup': breakup };
    };

    var load = function(use_string){
        var load_this = require.path + use_string + '.js';
        var func = new Function(["require", "module", "exports"], system.filesystem.get(load_this).contents);
        return func;
    };
})();

var output = '';
var print = function(message, label){
    output += "    ====> "+message+" --- "+label+"\n";
}

var tests = [
    'absolute', 
    'determinism', 
    'exactExports', 
    'hasOwnProperty', 
    'method', 
    'missing', 
    'nested', 
    'reflexive', 
    'relative', 
    'transitive', 
    'cyclic', 
    'monkeys'
];
function main(req){
    try {
        tests.forEach(function(test){
            require.moduleCache = {}; output += "\n";
            output += "#### TEST: "+test+"\n";
            require.path = 'interoperablejs/compliance/'+test+'/';
            require('program'); 
        });
    } catch(e) {
        print("ERROR", e);
    };
    return [200, ['Content-Type', 'text/plain'], output];
}

This is currently only runnable on a development branch deployment.

Hopefully I'll be able to pull it in as a generic option shortly.