module.exports = {
  devtool: 'inline-source-map',
  module: {
    rules: [{
      test: /\.js$/,
      loader: 'babel-loader',
      exclude: /node_modules/
    }, {
      test: /\.(css|scss)$/,
      loader: 'null-loader'
    }, {
      test: /\.(png|jpg|jpeg|gif|svg|woff|woff2|ttf|eot)$/,
      loader: 'file-loader'
    }, {
      test: /\.html$/,
      loader: 'raw-loader'
    }, {
      enforce: 'pre',
      test: /\.js$/,
      exclude: [
        /node_modules/,
        /\.spec\.js$/,
        /dev-server\.js/
      ],
      loader: 'istanbul-instrumenter-loader',
      query: {
        esModules: true
      }
    }]
  },
  devServer: {
    stats: 'minimal'
  }
};

'use strict';

module.exports = {
  devtool: 'inline-source-map',
  module: {
    rules: [{
      test: /\.js$/,
      loader: 'babel-loader',
      exclude: /node_modules/
    }, {
      test: /\.(css|scss)$/,
      loader: 'null-loader'
    }, {
      test: /\.(png|jpg|jpeg|gif|svg|woff|woff2|ttf|eot)$/,
      loader: 'file-loader'
    }, {
      test: /\.html$/,
      loader: 'raw-loader'
    }, {
      enforce: 'pre',
      test: /\.js$/,
      exclude: [
        /node_modules/,
        /\.spec\.js$/
      ],
      loader: 'istanbul-instrumenter-loader',
      query: {
        esModules: true
      }
    }]
  },
  devServer: {
    stats: 'minimal'
  }
};

--- 
+++ 
@@ -1,5 +1,3 @@
-'use strict';
-
 module.exports = {
   devtool: 'inline-source-map',
   module: {
@@ -21,7 +19,8 @@
       test: /\.js$/,
       exclude: [
         /node_modules/,
-        /\.spec\.js$/
+        /\.spec\.js$/,
+        /dev-server\.js/
       ],
       loader: 'istanbul-instrumenter-loader',
       query: {
Exclude dev-server file from coverage
