add test.

test/dashboard2/build/dev-client.js

@@ -0,0 +1,9 @@
+/* eslint-disable */
+require('eventsource-polyfill')
+var hotClient = require('webpack-hot-middleware/client?noInfo=true&reload=true')
+
+hotClient.subscribe(function (event) {
+  if (event.action === 'reload') {
+    window.location.reload()
+  }
+})