diff --git a/karma.config.js b/karma.config.js
index c224fafb..2f2c234d 100644
--- a/karma.config.js
+++ b/karma.config.js
@@ -1,6 +1,6 @@
-var webpack = require('webpack')
+const webpack = require('webpack')
 
-var testEntry = 'tests.webpack.js'
+const testEntry = 'tests.webpack.js'
 
 module.exports = function (config) {
   config.set({
@@ -30,6 +30,13 @@ module.exports = function (config) {
     singleRun: true,
     webpack: {
       devtool: 'inline-source-map',
+      // required by 'enzyme'
+      externals: {
+        'cheerio': 'window',
+        'react/addons': true,
+        'react/lib/ExecutionEnvironment': true,
+        'react/lib/ReactContext': true
+      },
       module: {
         loaders: [
           {
diff --git a/package.json b/package.json
index f09f87d4..995e874d 100644
--- a/package.json
+++ b/package.json
@@ -33,6 +33,7 @@
     "babel-preset-react": "^6.5.0",
     "babel-preset-stage-1": "^6.5.0",
     "del-cli": "^0.2.0",
+    "enzyme": "^2.3.0",
     "eslint": "^2.12.0",
     "eslint-config-standard": "^5.3.1",
     "eslint-config-standard-react": "^2.4.0",