@Test
 public void jsonUserInstanceShouldContainUrlAttribute() throws Exception {
   final JSONObject u = helper.getJsonResponse("/user/id/1");
   assertTrue(u.has("url"));
   assertEquals(helper.getBaseUrl() + "/user/id/1", u.get("url"));
 }
 @Test
 public void xmlUserInstanceShouldContainUrlAttribute() throws Exception {
   final User u = helper.getXmlResponse("/user/id/1", User.class);
   assertEquals(helper.getBaseUrl() + "/user/id/1", u.getUrl());
 }