karma.conf.js

var webpack = require('webpack');

module.exports = function (config) {
  config.set({
    browsers: [ 'PhantomJS' ], //run in Chrome
    autoWatch:  true,
    singleRun: true,
    frameworks: [ 'mocha' ], //use the mocha test framework
    files: [
      'tests.webpack.js' //just load this file
    ],
    preprocessors: {
      'tests.webpack.js': [ 'webpack', 'sourcemap' ] //preprocess with webpack and our sourcemap loader
    },
    reporters: [ 'dots', 'coverage' ], //report results in this format
    webpack: { //kind of a copy of your webpack config
      devtool: 'inline-source-map', //just do inline source maps instead of the default
      module: {
        loaders: [
          { test: /\.js$/, loader: 'babel-loader' }
        ],
        postLoaders: [ {
          test: /\.js$/,
          exclude: /(__test__|node_modules|examples)\//,
          loader: 'istanbul-instrumenter'
        } ]
      }
    },
    webpackServer: {
      noInfo: true //please don't spam the console when running in karma!
    },
    coverageReporter: {
      type: 'lcov',
      dir: 'coverage',
      subdir: '.'
    }
  });
};