When I run this test, it fails - Employee Module should get Employee by ID: timeout of 2000ms exceeded. Ensure the done() callback is being called in this test.

employee.js

var Employee = function() {

  var loadUserinfo = function(userid) {
    return $.ajax({
      type: 'GET',
      data:{userid: userid},
      url: '/employees.json',
      dataType: 'json',
      async: true,
      success: function(data) {
        return data;
      }
    });
  };

  var getData = function (userid) {
    return loadUserinfo(userid).done();
  };

  return {
    getData: getData,
  };
};

test.js

(function () {
  'use strict';

  describe('Employee Module', function() {
    var server,
        employeeJSON = {
          "employeeTemplate" : [
            {
              "userId": 1
            }
          ]
        };

    before(function () {
      server = sinon.fakeServer.create();
      server.respondWith(
        "GET",
        "/employees.json",
        [200, { "Content-Type": "application/json" }, JSON.stringify(employeeJSON)]
      );
    });

    after(function () {
      server.restore();
    });

    it('should get Employee by ID', function(done) {

      var employee = new Employee(),
          employeeData;

      employee.getData(1).done( function (data) {
        employeeData = data.employeeTemplate[0];
        assert.equal(employeeData.userId, 1, 'Employee ID equals 1');
        done();
      });
    });
  });
})();