Add Sinon to do better unit test

js/tests/index.html

@@ -25,6 +25,9 @@
     <link rel="stylesheet" href="vendor/qunit.css" media="screen">
     <script src="vendor/qunit.js"></script>
 
+    <!-- Sinon -->
+    <script src="vendor/sinon.min.js"></script>
+
     <script>
       // Disable jQuery event aliases to ensure we don't accidentally use any of them
       [