单元测试是代码质量的保障。JUnit 5 Mockito是Java测试的标准组合。本文讲解如何写出高质量测试。一、JUnit 5基础java复制下载class CalculatorTest { Test void testAdd() { Calculator calc new Calculator(); assertEquals(3, calc.add(1, 2)); } BeforeEach void setUp() { } AfterEach void tearDown() { } Test DisplayName(除法-除数为0抛异常) void testDivideByZero() { assertThrows(ArithmeticException.class, () - calc.divide(1, 0)); } }二、参数化测试java复制下载ParameterizedTest CsvSource({ 1, 2, 3, 0, 0, 0, -1, 1, 0 }) void testAdd(int a, int b, int expected) { assertEquals(expected, calc.add(a, b)); } ParameterizedTest ValueSource(strings {racecar, level, noon}) void testPalindrome(String s) { assertTrue(isPalindrome(s)); }三、Mockito基础java复制下载ExtendWith(MockitoExtension.class) class UserServiceTest { Mock private UserRepository userRepository; InjectMocks private UserService userService; Test void testGetUser() { User user new User(1L, Tom); when(userRepository.findById(1L)).thenReturn(Optional.of(user)); User result userService.getUser(1L); assertEquals(Tom, result.getName()); verify(userRepository, times(1)).findById(1L); } }四、常用Mockito APIjava复制下载// 返回值 when(mock.method()).thenReturn(value); when(mock.method()).thenThrow(new RuntimeException()); when(mock.method(anyString())).thenAnswer(inv - answer); // 验证 verify(mock).method(); verify(mock, times(2)).method(); verify(mock, never()).method(); verify(mock, timeout(1000)).method(); // 参数捕获 ArgumentCaptorUser captor ArgumentCaptor.forClass(User.class); verify(repo).save(captor.capture()); assertEquals(Tom, captor.getValue().getName()); // 静态方法Mockito 3.4 try (MockedStaticLocalDate mocked mockStatic(LocalDate.class)) { mocked.when(LocalDate::now).thenReturn(LocalDate.of(2024, 1, 1)); // ... }五、测试Controllerjava复制下载WebMvcTest(UserController.class) class UserControllerTest { Autowired private MockMvc mockMvc; MockBean private UserService userService; Test void testGetUser() throws Exception { when(userService.get(1L)).thenReturn(new UserDTO(1L, Tom)); mockMvc.perform(get(/api/users/1)) .andExpect(status().isOk()) .andExpect(jsonPath($.name).value(Tom)); } }六、测试Repositoryjava复制下载DataJpaTest class UserRepositoryTest { Autowired private UserRepository userRepository; Test void testFindByUsername() { userRepository.save(new User(null, Tom, 20)); OptionalUser user userRepository.findByUsername(Tom); assertTrue(user.isPresent()); } }七、测试覆盖率xml复制下载运行plugin groupIdorg.jacoco/groupId artifactIdjacoco-maven-plugin/artifactId version0.8.10/version executions execution goals goalprepare-agent/goal /goals /execution execution idreport/id phasetest/phase goals goalreport/goal /goals /execution /executions /plugin八、测试最佳实践遵循AAAArrange-Act-Assert一个测试只验证一个行为测试命名清晰should_xxx_when_yyy避免测试依赖顺序Mock外部依赖不Mock被测类覆盖率不是目标质量才是九、总结好的测试是重构的底气。JUnit 5 Mockito JaCoCo 是Java测试的黄金组合。养成写测试的习惯代码质量自然提升。
单元测试是代码质量的保障。JUnit 5 Mockito是Java测试的标准组合。本文讲解如何写出高质量测试。一、JUnit 5基础java复制下载class CalculatorTest { Test void testAdd() { Calculator calc new Calculator(); assertEquals(3, calc.add(1, 2)); } BeforeEach void setUp() { } AfterEach void tearDown() { } Test DisplayName(除法-除数为0抛异常) void testDivideByZero() { assertThrows(ArithmeticException.class, () - calc.divide(1, 0)); } }二、参数化测试java复制下载ParameterizedTest CsvSource({ 1, 2, 3, 0, 0, 0, -1, 1, 0 }) void testAdd(int a, int b, int expected) { assertEquals(expected, calc.add(a, b)); } ParameterizedTest ValueSource(strings {racecar, level, noon}) void testPalindrome(String s) { assertTrue(isPalindrome(s)); }三、Mockito基础java复制下载ExtendWith(MockitoExtension.class) class UserServiceTest { Mock private UserRepository userRepository; InjectMocks private UserService userService; Test void testGetUser() { User user new User(1L, Tom); when(userRepository.findById(1L)).thenReturn(Optional.of(user)); User result userService.getUser(1L); assertEquals(Tom, result.getName()); verify(userRepository, times(1)).findById(1L); } }四、常用Mockito APIjava复制下载// 返回值 when(mock.method()).thenReturn(value); when(mock.method()).thenThrow(new RuntimeException()); when(mock.method(anyString())).thenAnswer(inv - answer); // 验证 verify(mock).method(); verify(mock, times(2)).method(); verify(mock, never()).method(); verify(mock, timeout(1000)).method(); // 参数捕获 ArgumentCaptorUser captor ArgumentCaptor.forClass(User.class); verify(repo).save(captor.capture()); assertEquals(Tom, captor.getValue().getName()); // 静态方法Mockito 3.4 try (MockedStaticLocalDate mocked mockStatic(LocalDate.class)) { mocked.when(LocalDate::now).thenReturn(LocalDate.of(2024, 1, 1)); // ... }五、测试Controllerjava复制下载WebMvcTest(UserController.class) class UserControllerTest { Autowired private MockMvc mockMvc; MockBean private UserService userService; Test void testGetUser() throws Exception { when(userService.get(1L)).thenReturn(new UserDTO(1L, Tom)); mockMvc.perform(get(/api/users/1)) .andExpect(status().isOk()) .andExpect(jsonPath($.name).value(Tom)); } }六、测试Repositoryjava复制下载DataJpaTest class UserRepositoryTest { Autowired private UserRepository userRepository; Test void testFindByUsername() { userRepository.save(new User(null, Tom, 20)); OptionalUser user userRepository.findByUsername(Tom); assertTrue(user.isPresent()); } }七、测试覆盖率xml复制下载运行plugin groupIdorg.jacoco/groupId artifactIdjacoco-maven-plugin/artifactId version0.8.10/version executions execution goals goalprepare-agent/goal /goals /execution execution idreport/id phasetest/phase goals goalreport/goal /goals /execution /executions /plugin八、测试最佳实践遵循AAAArrange-Act-Assert一个测试只验证一个行为测试命名清晰should_xxx_when_yyy避免测试依赖顺序Mock外部依赖不Mock被测类覆盖率不是目标质量才是九、总结好的测试是重构的底气。JUnit 5 Mockito JaCoCo 是Java测试的黄金组合。养成写测试的习惯代码质量自然提升。
