You can’t load CJS/Node.js modules in a browser without running them in Browserify; that is the entire purpose of Browserify. You need to pre-Browserify the modules, switch to using AMD modules instead of CJS modules for your application, or introduce a proxy that converts the modules on the fly.
If you are trying to load CJS modules in Node.js through Intern, you need to use the intern/dojo/node
module to facilitate that load:
define([
'intern!object',
'intern/chai!assert',
'intern/dojo/node!src/js/tested'
], function (registerSuite, assert, tested) {
registerSuite({
// ...
More information about this in the Testing Non-AMD code section of the documentation.