karma.conf.js

const webpack = require('webpack');

module.exports = function karmaMain(config) {
  config.set({

    browserNoActivityTimeout: 30000,

    browsers: [process.env.CONTINUOUS_INTEGRATION ? 'Firefox' : 'Chrome'],

    singleRun: process.env.CONTINUOUS_INTEGRATION === 'true',

    frameworks: ['mocha'],

    files: [
      'tests.webpack.js',
    ],

    preprocessors: {
      'tests.webpack.js': ['webpack', 'sourcemap'],
    },

    reporters: ['dots'],

    webpack: {
      devtool: 'inline-source-map',
      module: {
        loaders: [
          {test: /\.js$/, loader: 'babel-loader'},
        ],
      },
      plugins: [
        new webpack.DefinePlugin({
          'process.env.NODE_ENV': JSON.stringify('test'),
        }),
      ],
    },

    webpackServer: {
      noInfo: true,
    },

  });
};