fix

package.json

@@ -12,7 +12,12 @@
     "presets": "env"
   },
   "eslintConfig": {
-    "extends": "airbnb-base"
+    "extends": "airbnb-base",
+    "globals": {
+      "window": true,
+      "document": true,
+      "alert": true
+    }
   },
   "devDependencies": {
     "babel-core": "^6.26.0",

src/js/app.js

@@ -1,4 +0,0 @@
-// testのサンプルです。
-const sum = (a, b) => a + b;
-
-export default sum;

src/js/example.js

@@ -0,0 +1,4 @@
+// testのサンプルです。
+const sum = (a, b) => a + b;
+
+export default sum;

src/js/test/app.test.js → src/js/test/example.test.js

@@ -1,4 +1,4 @@
-import sum from '../app';
+import sum from '../example';
 
 it('adds 1 + 2 to equal 3', () => {
   expect(sum(1, 2)).toBe(3);

webpack.config.js

@@ -39,18 +39,14 @@ module.exports = [
       filename: 'style.css'
     },
     module: {
-      rules: [
-        {
-          test: /\.scss$/,
-          use: ExtractTextPlugin.extract({
-            fallback: 'style-loader',
-            use: ['css-loader', 'sass-loader']
-          })
-        }
-      ]
+      rules: [{
+        test: /\.scss$/,
+        use: ExtractTextPlugin.extract({
+          fallback: 'style-loader',
+          use: ['css-loader', 'sass-loader']
+        })
+      }]
     },
-    plugins: [
-      new ExtractTextPlugin('style.css')
-    ]
+    plugins: [ new ExtractTextPlugin('style.css') ]
   }
 ];