.forward（req，resp）之后的HttpServletRequest有什么问题？

Question

I have a test for simple Servlet which get jsp file. In this servlet action request.setAttribute("key", "value") but after call .forward() when I do request.getAttribute("key") I'm get null . Why this happen? This behavior determines forward or reason in mock object?

This is doPost of Servlet:

@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp)
        throws ServletException, IOException {

    final boolean success = addUserInDatabase(req);

    if (success) req.setAttribute("serverAnswer", EDIT_SUCCESS.get());//this write value
    else req.setAttribute("serverAnswer", ERR_UNIQUE_L_P.get());

    req.getRequestDispatcher(ANSWER.get())
            .forward(req, resp);
}

This is test:

//mock http.
HttpServletRequest request = mock(HttpServletRequest.class);
HttpServletResponse response = mock(HttpServletResponse.class);


RequestDispatcher dispatcher = mock(RequestDispatcher.class);
when(request.getRequestDispatcher(ANSWER.get()))
                  .thenReturn(dispatcher);
servlet.doPost(request, response);
String result = (String) request.getAttribute("serverAnswer");//get value
Assert.assertThat(result, is(EDIT_SUCCESS.get()));// result == null

Why I get Null? Is it possible to get value of setAttribute after call forward ? How to test this behavior? Thank You.

Answer 1

try request.getAttribute("serverAnswer").toString(); and use .include(request, response); .

Answer 2

If you add String result = (String)req.getAttribute("serverAnswer"); just before calling req.getRequestDispatcher(ANSWER.get()) on your servlet and check value of result it would still be null.

The reason is your request object is not real but mocked. you have to do something like this.

when(request.getAttribute(eq("serverAnswer"))).thenReturn(EDIT_SUCCESS.get());