atom/docs/advanced/node-modules.md

Developing Node Modules

Atom contains a number of packages that are Node modules instead of Atom packages. If you want to make changes to the Node modules, for instance atom-keymap, you have to link them into the development environment differently than you would a normal Atom package.

Linking a Node Module Into Your Atom Dev Environment

Here are the steps to run a local version of a node module not an apm within Atom. We're using atom-keymap as an example:

$ git clone https://github.com/atom/atom-keymap.git
$ cd atom-keymap
$ npm install
$ npm link
$ apm rebuild # This is the special step, it makes the npm work with Atom's version of Node
$ cd WHERE-YOU-CLONED-ATOM
$ npm link atom-keymap
$ atom # Should work!

After this, you'll have to npm install and apm rebuild when you make a change to the node module's code.