@Test
public void testGetQuestionGroupWhenIdIsNull() throws SystemException {

    when(httpServletRequest.getParameter("questionGroupId")).thenReturn(null);
    String view = questionGroupController.getQuestionGroup(model, httpServletRequest);
    assertThat(view, Is.is("viewQuestionGroupDetail"));
    verify(httpServletRequest, times(1)).getParameter("questionGroupId");
    verify(questionnaireServiceFacade, times(0)).getQuestionGroupDetail(Matchers.anyInt());
    verify(model).addAttribute("error_message_code", QuestionnaireConstants.INVALID_QUESTION_GROUP_ID);
}