@Test
@SuppressWarnings("unchecked")
public void queryStringUser() {

  MDC.remove("user");
  HttpRequestContext request = Mockito.mock(HttpRequestContext.class);
  Mockito.when(request.getUserPrincipal()).thenReturn(null);
  MultivaluedMap map = Mockito.mock(MultivaluedMap.class);
  Mockito.when(map.getFirst(UserProvider.USER_NAME_PARAM)).thenReturn("foo");
  Mockito.when(request.getQueryParameters()).thenReturn(map);
  HttpContext context = Mockito.mock(HttpContext.class);
  Mockito.when(context.getRequest()).thenReturn(request);
  UserProvider up = new UserProvider();
  assertEquals(up.getValue(context).getName(), "foo");
  assertEquals(MDC.get("user"), "foo");
}