var webpack = require('webpack');

module.exports = function (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$/, exclude: /node_modules/, loader: 'babel?optional=es7.classProperties&plugins=object-assign' }
        ]
      },
      plugins: [
        new webpack.DefinePlugin({
          'process.env.NODE_ENV': JSON.stringify('test')
        })
      ]
    },

    webpackServer: {
      noInfo: true
    }

  });
};

var webpack = require('webpack');

module.exports = function (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$/, exclude: /node_modules/, loader: 'babel-loader?optional=es7.classProperties' }
        ]
      },
      plugins: [
        new webpack.DefinePlugin({
          'process.env.NODE_ENV': JSON.stringify('test')
        })
      ]
    },

    webpackServer: {
      noInfo: true
    }

  });
};

--- 
+++ 
@@ -25,7 +25,7 @@
       devtool: 'inline-source-map',
       module: {
         loaders: [
-          { test: /\.js$/, exclude: /node_modules/, loader: 'babel?optional=es7.classProperties&plugins=object-assign' }
+          { test: /\.js$/, exclude: /node_modules/, loader: 'babel-loader?optional=es7.classProperties' }
         ]
       },
       plugins: [
Add object-assign plugin to karma
