Spring Boot 测试最佳实践

🧪 1. 测试分层策略 (Testing Strategy / Pyramid)

核心思想：多写单元测试，少写E2E测试
Core idea: More unit tests, fewer E2E tests

        E2E Tests（少 / Few）
     Integration Tests（中 / Medium）
Unit Tests（多 / Many）

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✅ 2. 单元测试最佳实践 (Unit Testing Best Practices)

👉 使用：JUnit + Mockito

✔ 原则 / Principles

• 只测试一个类 (Test one class only)

• Mock 外部依赖 (Mock dependencies)

• 不连接数据库/网络 (No DB / network)

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✔ 示例 / Example

@ExtendWith(MockitoExtension.class)
class UserServiceTest {

    @Mock
    private UserRepository userRepository;

    @InjectMocks
    private UserService userService;

    @Test
    void shouldReturnUser_whenUserExists() {
        User user = new User(1L, "Neo");

        when(userRepository.findById(1L)).thenReturn(Optional.of(user));

        User result = userService.getUserById(1L);

        assertEquals("Neo", result.getName());
    }
}

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💡 关键点 / Key Points

• 使用 @Mock 模拟依赖

• 使用 @InjectMocks 注入被测类

• Use @Mock to isolate dependencies

• Use @InjectMocks for target class

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🔗 3. 集成测试最佳实践 (Integration Testing)

👉 使用：@SpringBootTest

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✔ 原则 / Principles

• 测试模块之间真实交互 (Test real interactions)

• 可以连接数据库 (DB allowed)

• 使用测试数据库 (Use test DB, e.g. H2)

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✔ 示例 / Example

@SpringBootTest
@Transactional
class UserServiceIntegrationTest {

    @Autowired
    private UserService userService;

    @Test
    void shouldSaveUser() {
        User user = new User(null, "Neo");

        User saved = userService.save(user);

        assertNotNull(saved.getId());
    }
}

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💡 建议 / Tips

• 使用 H2 内存数据库 (Use H2 in-memory DB)

• 使用 @Transactional 自动回滚

• Rollback after each test

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🌐 4. Controller / API 测试 (Web Layer Testing)

👉 使用：@WebMvcTest + MockMvc

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✔ 示例 / Example

@WebMvcTest(UserController.class)
class UserControllerTest {

    @Autowired
    private MockMvc mockMvc;

    @MockBean
    private UserService userService;

    @Test
    void shouldReturnUser() throws Exception {
        when(userService.getUserById(1L))
            .thenReturn(new User(1L, "Neo"));

        mockMvc.perform(get("/users/1"))
               .andExpect(status().isOk())
               .andExpect(jsonPath("$.name").value("Neo"));
    }
}

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💡 关键点 / Key Points

• 只加载 Web 层 (Load only web layer)

• 使用 @MockBean 替代真实 Service

• Use MockMvc to simulate HTTP calls

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🧩 5. 数据库测试 (Repository Testing)

👉 使用：@DataJpaTest

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✔ 示例 / Example

@DataJpaTest
class UserRepositoryTest {

    @Autowired
    private UserRepository userRepository;

    @Test
    void shouldFindByName() {
        userRepository.save(new User(null, "Neo"));

        Optional<User> user = userRepository.findByName("Neo");

        assertTrue(user.isPresent());
    }
}

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💡 特点 / Features

• 只加载 JPA 相关组件

• Faster than full Spring context

• 默认使用内存数据库

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🔁 6. 回归测试策略 (Regression Strategy)

✔ 建议 / Recommendations

• 每次提交运行单元测试

  Run unit tests on every commit

• CI/CD 运行全部测试

  Run all tests in pipeline

• 关键路径加 E2E

  Add E2E for critical flows

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🚀 7. 测试命名规范 (Naming Convention)

👉 推荐格式 / Recommended format:

should + ExpectedResult + when + Condition

示例 / Example

• shouldReturnUser_whenUserExists

• shouldThrowException_whenUserNotFound

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⚠️ 8. 常见错误 (Common Mistakes)

❌ 写太多集成测试 → 慢

Too many integration tests → slow

❌ 单元测试依赖数据库

Unit test depends on DB

❌ 不做Mock

No mocking → not isolated

❌ 测试没有断言

No assertions

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🧠 9. 最佳实践总结 (Final Summary)

类型	工具	用途
单元测试	JUnit + Mockito	快速、隔离
集成测试	@SpringBootTest	模块协作
Web测试	@WebMvcTest	API层
数据库测试	@DataJpaTest	JPA

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💡 一句话总结 (One-line takeaway)

👉 80% 单元测试 + 15% 集成测试 + 5% E2E

👉 Focus on unit tests, use integration wisely