Unit test Spring and PowerMock - Getting null pointer in request.getParameter value

Hi I have the following code to test:

@RequestMapping(value = "/displayPages", method = RequestMethod.GET)
    public ModelAndView errorPage(ModelMap model, HttpServletRequest request) {
        String token = (request != null) ? request.getParameter("tok") : "";
        boolean requestP = ESAPI.validator().isValidInput("Request Param", tok, "HTTPParameterValue", 1, false);
        if (requestP || token.contains(msg.getMessage("techErr.tok", new Object[]{}, Constants.LOCAL))) {
            return new ModelAndView("dispError");
        } else {
            return new ModelAndView("login");
        }

    }

Part of my unit test class is shown below:

  @RunWith(PowerMockRunner.class)
    @PrepareForTest({ESAPI.class})
    public class ApplicationConTest {

          @InjectMocks
        private ApplicationCont appController;

        private MockMvc mockMvc;

        ....

         @Before
        public void setup() {

            MockHttpServletRequest request = new MockHttpServletRequest();


            MockHttpSession session = new MockHttpSession();
            request.setSession(session);
            RequestContextHolder.setRequestAttributes(new ServletRequestAttributes(request));

            this.mockMvc = MockMvcBuilders.standaloneSetup(appController).build();

        }

 @Test
    public void errorPages_ExpectLogout() throws Exception {

        String returnVal = "test";

        HttpServletRequest request = mock(HttpServletRequest.class);       


        when(request.getParameter("tok")).thenReturn("dummuy value");



        when(msg.getMessage("techErr.tok",new Object[]{},Constants.LOCAL)).thenReturn(returnVal);

        //msg.getMessage("techErr.tok", new Object[]{}, Constants.LOCAL)


           mockMvc.perform(get("/errorPages"))
                .andExpect(view().name("logout")
                );
    }

When I execute the code the String tok is null and i get a null pointer exception. However as showed above I am returning a dummy value, any advice why tok is null?

Thanks in advance for any help.