Unit Testing Sinon.js and sinon.stub in Safari

HTML

<link rel="stylesheet" href="http://code.jquery.com/qunit/qunit-1.12.0.css">
<script src="http://code.jquery.com/qunit/qunit-1.12.0.js"></script>
<script src="http://sinonjs.org/releases/sinon-1.7.3.js"></script>
<script src="http://sinonjs.org/releases/sinon-qunit-1.0.0.js"></script>
<script>
// some global function
function myFunc() {
  return true;
}
    
var oldMyFunc = myFunc;
</script>
<div id="qunit"></div>
<div id="qunit-fixture"></div>

JavaScript

var testObj = { hi: null}