public class LoginAction extends Action {

    public ActionForward perform(ActionMapping mapping,
                                 ActionForm form,
                                 HttpServletRequest request,
                                 HttpServletResponse response)
    {

        String username = ((LoginForm) form).getUsername();
        String password = ((LoginForm) form).getPassword();

        ActionErrors errors = new ActionErrors();

        if ((!username.equals("deryl")) || (!password.equals("radar")))
            errors.add("password",new ActionError("error.password.mismatch"));

        if (!errors.empty()) {
            saveErrors(request,errors);
            return mapping.findForward("login");
        }

// store authentication info on the session
        HttpSession session = request.getSession();
        session.setAttribute("authentication", username);

        // Forward control to the specified success URI
        return mapping.findForward("success");

    }

public class TestLoginAction extends MockStrutsTestCase {

    public void setUp() { super.setUp(); }

    public void tearDown() { super.tearDown(); }

    public TestLoginAction(String testName) { super(testName); }

    public void testSuccessfulLogin() {}
}

public class TestLoginAction extends MockStrutsTestCase {

    public TestLoginAction(String testName) { super(testName); }

    public void testSuccessfulLogin() {
       setRequestPathInfo("/login");
    }
}

public class TestLoginAction extends MockStrutsTestCase {

    public TestLoginAction(String testName) { super(testName); }

    public void testSuccessfulLogin() {
       setRequestPathInfo("/login");
       addRequestParameter("username","deryl");
       addRequestParameter("password","radar");
    }
}

public class TestLoginAction extends MockStrutsTestCase {

    public TestLoginAction(String testName) { super(testName); }

    public void testSuccessfulLogin() {
       setRequestPathInfo("/login");
       addRequestParameter("username","deryl");
       addRequestParameter("password","radar");
       actionPerform();
    }
}

public class TestLoginAction extends MockStrutsTestCase {

    public TestLoginAction(String testName) { super(testName); }

    public void testSuccessfulLogin() {
       setRequestPathInfo("/login");
       addRequestParameter("username","deryl");
       addRequestParameter("password","radar");
       actionPerform();
       verifyForward("success");
    }
}

public class TestLoginAction extends MockStrutsTestCase {

    public TestLoginAction(String testName) { super(testName); }

    public void testSuccessfulLogin() {
       setRequestPathInfo("/login");
       addRequestParameter("username","deryl");
       addRequestParameter("password","radar");
       actionPerform();
       verifyForward("success");
       assertEquals("deryl",(String) getSession().getAttribute("authentication"));
    }
}

public class TestLoginAction extends MockStrutsTestCase {

    public TestLoginAction(String testName) { super(testName); }

    public void testSuccessfulLogin() {
       setRequestPathInfo("/login");
       addRequestParameter("username","deryl");
       addRequestParameter("password","radar");
       actionPerform();
       verifyForward("success");
       assertEquals("deryl",(String) getSession().getAttribute("authentication"));
       verifyNoActionErrors();
    }
}

public void testFailedLogin() {

    addRequestParameter("username","deryl");
    addRequestParameter("password","express");
    setRequestPathInfo("/login");
    actionPerform();
    verifyForward("login");
    verifyActionErrors(new String[] {"error.password.mismatch"});
    assertNull((String) getSession().getAttribute("authentication"));
}

URL:http://homepage2.nifty.com/ymagic/struts/OtherTranslate/StrutsTestCase/index.html