Junit 用 eclipse 测试 servlet

Question

I'm not familiar with Junit testing. For example, how can I write a Unit test for this servlet? I really don't know where to start, please.?! Obviously he accesses the database and I don't know how to do the test to check if the credentials entered are present in the db. Could you give me an example about this servlet please?

/**
 * Servlet implementation class LoginPatient
 */
@WebServlet("/LoginPatient")
public class LoginPatient extends HttpServlet {
    private static final long serialVersionUID = 1L;

    /**
     * @see HttpServlet#HttpServlet()
     */
    public LoginPatient() {
        super();
        // TODO Auto-generated constructor stub
    }

    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doPost(request, response);
    }

    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        String fiscal_code=request.getParameter("fiscal_code");
        String user_password= request.getParameter("user_password");
        PrintWriter out=response.getWriter();
        ProfileManager pM=new ProfileManager();
        UserBean patient= pM.ReturnPatientByKey(fiscal_code, user_password);

        if(patient != null) {
            HttpSession session= request.getSession();
            session.setAttribute( "user" , patient);
            session.setMaxInactiveInterval(-1);
            out.println("1");
        }

        else {
            out.println("0"); 
        }
    }

}

Answer 1

A unit test for this servlet should not actually access the DB. It should test that the servlet behaves correctly given the various results ProfileManager may return.

You need to use dependency injection so that you can mock ProfileManager in your unit test.

How you do this depends on your framework. In spring you would say:

@Component
public class LoginPatient extends HttpServlet {
   ...
   @Autowired
   public LoginPatient(ProfileManager profileManager) { ... }
   ...
}

Then in your test use Mockito (this is a sketch not compilable code)

public void testPresent() {
   // mock the request and response, and the session
   HttpServletRequest req = mock(HttpServletRequest.class);
   Session session = mock(HttpSession.class);
   when(req.getSession()).thenReturn(session);
   ...
   // you might want to mock the UserBean instance too
   ProfileManager pm = mock(ProfileManager.class);
   when(pm.ReturnPatientByKey("aCode", "aPassword")).thenReturn(new UserBean(...));
   LoginPatient servlet = new LoginPatient(pm);
   servlet.doPost(req, res);
   // verify that the session had the right things done to it
}