Unit Testing Ajax with Sinon.js and QUnit

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>
<div id="qunit"></div>
<div id="qunit-fixture"></div>

JavaScript

test("data from server", function () {
   var server = this.sandbox.useFakeServer();
    server.respondWith("GET", "/mytest",
    [200, { "Content-Type": "application/json" },
      '[{ "id": "52", "name": "Rock" }]']);
 var callback = this.spy();
 $.ajax({
 url: "/mytest",
 success: callback
        });

  server.respond();
 equal(server.requests.length, 1, "server request length");
 ok(callback.called, "spy called once"); //failed
 ok(callback.calledWith([{ id: "52", name: "Rock" }]));       //failed
});