public ModelAndView idpSelection(HttpServletRequest request, Model model) { Authentication auth = SecurityContextHolder.getContext().getAuthentication(); ModelAndView modelAndView = new ModelAndView(); if (auth == null) { LOG.debug("Current authentication instance from security context is null"); }else { LOG.debug("Current authentication instance from security context: " + this.getClass().getSimpleName()); } if (auth == null || (auth instanceof AnonymousAuthenticationToken)) { Set<String> idps = metadata.getIDPEntityNames(); for (String idp : idps) { LOG.info("Configured Identity Provider for SSO: " + idp); } model.addAttribute("idps", idps); modelAndView.setViewName("pages/discovery"); } else { LOG.warn("The current user is already logged."); modelAndView.setView(new RedirectView("/api/saml/landing",true,false)); } return modelAndView; }帮我用mokito写一下单元测试

当使用Mockito进行单元测试时，我们首先需要创建一个测试类，并导入所需的依赖项。在测试类中，我们可以使用Mockito的注解和方法来创建模拟对象和设置模拟对象的行为。

下面是使用Mockito编写的一个可能的单元测试示例：

import static org.mockito.Mockito.*;

@RunWith(MockitoJUnitRunner.class)
public class YourTestClass {

    @InjectMocks
    private YourController yourController;

    @Mock
    private HttpServletRequest request;

    @Mock
    private Model model;

    @Mock
    private Authentication authentication;

    @Mock
    private SecurityContext securityContext;

    @Mock
    private AnonymousAuthenticationToken anonymousAuthenticationToken;

    @Mock
    private Metadata metadata;

    @Before
    public void setup() {
        when(request.getAuthentication()).thenReturn(authentication);
        when(SecurityContextHolder.getContext()).thenReturn(securityContext);
        when(securityContext.getAuthentication()).thenReturn(authentication);
        when(authentication instanceof AnonymousAuthenticationToken).thenReturn(anonymousAuthenticationToken);
        when(metadata.getIDPEntityNames()).thenReturn(new HashSet<>(Arrays.asList("idp1", "idp2")));

        yourController = new YourController();
    }

    @Test
    public void testIdpSelection() {
        ModelAndView expectedModelAndView = new ModelAndView();
        expectedModelAndView.setViewName("pages/discovery");
        expectedModelAndView.addObject("idps", new HashSet<>(Arrays.asList("idp1", "idp2")));

        ModelAndView actualModelAndView = yourController.idpSelection(request, model);

        assertEquals(expectedModelAndView.getViewName(), actualModelAndView.getViewName());
        assertEquals(expectedModelAndView.getModel().get("idps"), actualModelAndView.getModel().get("idps"));
    }
}

上述示例中，我们使用了`@RunWith(MockitoJUnitRunner.class)`注解来初始化模拟对象并注入到测试类中。然后，我们使用`@Mock`注解来创建模拟对象，并使用`when()`方法来设置模拟对象的行为。在`setup()`方法中，我们设置了模拟对象在测试中的行为。在`testIdpSelection()`方法中，我们调用了被测试的方法，并使用断言来验证预期的结果与实际结果是否相符。

请注意，这只是一个示例，您可能需要根据您的实际代码进行适当的修改。此外，请确保在测试类中导入正确的依赖项。