webpack.server.test.config.js

const nodeExternals = require('webpack-node-externals')

module.exports = {
  module: {
    loaders: [
      {
        test: /\.js$/,
        exclude: /node_modules/,
        loader: 'babel'
      }
    ]
  },
  target: 'node',
  node: {
    __dirname: false,
    __filename: false
  },
  externals: [nodeExternals()],
  devtool: 'source-map'
}