Preprocessor which makes environment variables available to your tests.

The easiest way is to keep karma-env-preprocessor as a devDependency in your package.json.

{
  "devDependencies": {
    "karma": "~0.10",
    "karma-env-preprocessor": "~0.1"
  }
}

You can simple do it by:

npm install karma-env-preprocessor --save-dev

To load karma-env-preprocessor into Karma you should add it to the plugins array in the Karma configuration file. For more information see the Plugins section of the Karma documentation.

Any files you preprocess using this plugin will be affected, e.g for all JavaScript files:

// karma.conf.js
module.exports = function(config) {
  config.set({
    preprocessors: {
      '**/*.js': ['env']
    },

    envPreprocessor: [
      'PATH',
      'HOME'
    ],

    plugins: [
      'karma-env-preprocessor'
    ],
  });
};

This preprocessor uses process.env to read the value of each environment variable specified in envPreprocessor and publishes them in the global window.__env__, so you can read these values in your tests.

For example, the above configuration will be served as:

window.__env__ = window.__env__ || []
window.__env__['PATH'] = '/usr/sbin:/usr/bin:/sbin:/bin';
window.__env__['HOME'] = '/home/jsok';

For more information on Karma see the homepage.