Mock & Mockito是什么，怎么用?

    org.mockito    mockito-core    5.10.0    test

@ExtendWith(MockitoExtension.class)class UserControllerTest {    @Mock    private UserService userService;    @InjectMocks    private UserController userController;    @Test    void testGetUserById() {        User mockUser = new User(1, "张三");        when(userService.getUserById(1)).thenReturn(mockUser);        User result = userController.getUser(1);        assertEquals("张三", result.getName());        verify(userService).getUserById(1);    }}

verify(userService).getUserById(1); // 验证是否调用了该方法verify(userService, times(1)).getUserById(1); // 验证调用了一次

public class AdministratorServiceImplTest {      @InjectMocks      private AdministratorServiceImpl administratorService;      @Mock      private AdministratorMapper administratorMapper;      @BeforeEach      void setUp() {          // 初始化 Mockito 注解          MockitoAnnotations.openMocks(this);      }      // ---------- getAdminByName ----------      @Test      void testGetAdminByName_Success() {          Administrator mockAdmin = new Administrator();          mockAdmin.setAdminName("admin");          when(administratorMapper.selectOne(any(QueryWrapper.class))).thenReturn(mockAdmin);          Administrator result = administratorService.getAdminByName("admin");          assertEquals("admin", result.getAdminName());      }      @Test      void testGetAdminByName_EmptyName() {          assertErrorCode(() -> administratorService.getAdminByName(""), ErrorCodes.INVALID_PARAMETER);      }      @Test      void testGetAdminByName_NotFound() {          when(administratorMapper.selectOne(any(QueryWrapper.class))).thenReturn(null);          assertErrorCode(() -> administratorService.getAdminByName("unknown"), ErrorCodes.NOT_FOUND);      }      // ---------- updatePassword ----------      @Test      void testUpdatePassword_Success() {          Administrator admin = new Administrator();          admin.setAdminId(1L);          admin.setAdminPassword("old");          when(administratorMapper.selectById(1L)).thenReturn(admin);          when(administratorMapper.updateById(any())).thenReturn(1);          boolean result = administratorService.updatePassword(1L, "newPwd");          assertTrue(result);          assertEquals("newPwd", admin.getAdminPassword());      }      @Test      void testUpdatePassword_InvalidId() {          assertErrorCode(() -> administratorService.updatePassword(0L, "pwd"), ErrorCodes.INVALID_PARAMETER);      }      @Test      void testUpdatePassword_EmptyPassword() {          assertErrorCode(() -> administratorService.updatePassword(1L, "  "), ErrorCodes.INVALID_PARAMETER);      }      @Test      void testUpdatePassword_AdminNotFound() {          when(administratorMapper.selectById(1L)).thenReturn(null);          assertErrorCode(() -> administratorService.updatePassword(1L, "pwd"), ErrorCodes.NOT_FOUND);      }      // ---------- getAllAdministrators ----------      @Test      void testGetAllAdministrators() {          List<Administrator> mockList = Arrays.asList(new Administrator(), new Administrator());          when(administratorMapper.selectList(any())).thenReturn(mockList);          List<Administrator> result = administratorService.getAllAdministrators();          assertEquals(2, result.size());      }      // ---------- doLogin ----------      @Test      void testDoLogin_NullInput() {          assertNull(administratorService.doLogin(null));      }      @Test      void testDoLogin_EmptyFields() {          Administrator a = new Administrator();          assertNull(administratorService.doLogin(a));      }      @Test      void testDoLogin_NotFound() {          Administrator input = new Administrator();          input.setAdminName("admin");          input.setAdminPassword("123");          when(administratorMapper.selectList(any())).thenReturn(Collections.emptyList());          assertNull(administratorService.doLogin(input));      }      @Test      void testDoLogin_PasswordMismatch() {          Administrator input = new Administrator();          input.setAdminName("admin");          input.setAdminPassword("wrong");          Administrator dbAdmin = new Administrator();          dbAdmin.setAdminName("admin");          dbAdmin.setAdminPassword("correct");          when(administratorMapper.selectList(any())).thenReturn(List.of(dbAdmin));          assertNull(administratorService.doLogin(input));      }      @Test      void testDoLogin_Success() {          Administrator input = new Administrator();          input.setAdminName("admin");          input.setAdminPassword("123");          Administrator dbAdmin = new Administrator();          dbAdmin.setAdminName("admin");          dbAdmin.setAdminPassword("123");          when(administratorMapper.selectList(any())).thenReturn(List.of(dbAdmin));          Administrator result = administratorService.doLogin(input);          assertNotNull(result);          assertEquals("admin", result.getAdminName());      }      private void assertErrorCode(Runnable runnable, int expectedCode) {          BusinessException exception = assertThrows(BusinessException.class, runnable::run);          assertEquals(expectedCode, exception.getCode());      }  }