add basic test

package.json

@@ -7,7 +7,7 @@
     "doc": "docs"
   },
   "scripts": {
-    "test": "echo \"Error: no test specified\" && exit 1",
+    "test": "./test.sh",
     "build": "./build.js"
   },
   "repository": {

test.sh

@@ -0,0 +1,12 @@
+#!/bin/sh
+
+npm run build
+output=$( git diff build )
+
+if [ -z "$output" ]
+then
+    break
+else
+    echo "Build doesn't match, wanna run \`npm run build\`?"
+    exit 1;
+fi