A Karma plugin. Test CommonJS modules.
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A Karma plugin that allows testing CommonJS modules in the browser.


If you're using Browserify to compile your projects, you should consider karma-browserify which runs Browserify directly. The cost is slightly slower builds (but not too bad, thanks to an incremental loading algorithm) and somewhat messier stack traces. The benefit is support for the full Browserify API and automatic discovery of 'require'd files.


  1. Provides a lightweight commonjs wrapper around your code
  2. Supports Node's require algorithm
  3. Only reloads files that change
  4. Provides stack traces that point to your original files
  5. Requires you to specify files in the Karma config file


  1. Creates a temporary bundle using Browserify
  2. Supports the full Browserify API, including transforms, plugins, and shims for Node globals
  3. Uses watchify to perform incremental rebuilds
  4. Can use source maps to provide useful stack traces
  5. Automatically includes required files


The easiest way is to keep karma-commonjs as a devDependency:

npm install karma-commonjs --save-dev

which should result in the following entry in your package.json:

  "devDependencies": {
    "karma": "~0.10",
    "karma-commonjs": "~0.2"


// karma.conf.js
module.exports = function(config) {
    frameworks: ['jasmine', 'commonjs'],
    files: [
      // your tests, sources, ...

    preprocessors: {
      '**/*.js': ['commonjs']

Additionally you can specify a root folder (relative to project's directory) which is used to look for required modules:

commonjsPreprocessor: {
  modulesRoot: 'some_folder'  

When not specified the root folder defaults to the karma.basePath/node_modules configuration option.

For an example project, check out Karma's client tests.

For more information on Karma see the homepage.