rv.setUrl("http://url.somewhere.com");
rv.setHttp10Compatible(false);
MockHttpServletRequest request = createRequest();
MockHttpServletResponse response = new MockHttpServletResponse();
request.setAttribute(DispatcherServlet.OUTPUT_FLASH_MAP_ATTRIBUTE, new FlashMap());
request.setAttribute(DispatcherServlet.FLASH_MAP_MANAGER_ATTRIBUTE, new SessionFlashMapManager());
rv.render(new HashMap<String, Object>(), request, response);
assertEquals(303, response.getStatus());
assertEquals("http://url.somewhere.com", response.getHeader("Location"));
}