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Spring Boot 測試全攻略：從基礎到實戰的完整指南

3 min read

Summary

EN: A comprehensive Traditional Chinese guide to testing in Spring Boot, covering the full testing pyramid from unit tests to integration tests and E2E tests. Topics include the rationale for automated testing, JUnit 5 fundamentals, Spring Boot Test Starter configuration, Mockito for mocking, and testing strategies. The article is very long (exceeded token limit during reading) but the visible portion covers fundamentals through the test pyramid structure.

ZH: 本文以繁體中文全面介紹 Spring Boot 測試，涵蓋從單元測試到整合測試及端對端測試的完整測試金字塔。包含自動化測試的理由、JUnit 5 基礎、Spring Boot Test Starter 配置、Mockito mock 框架，以及各層級的測試策略。文章篇幅較長（讀取時超出限制），可見部分涵蓋基礎概念與測試金字塔結構。

Key Points

  • Test pyramid: Unit tests (fast, isolated) → Integration tests (slower, tests interactions) → E2E tests (slowest, tests full flow)
  • JUnit 5: @Test, @BeforeEach, @AfterEach, @DisplayName, parameterized tests
  • Spring Boot Test Starter: @SpringBootTest loads full application context; @WebMvcTest loads only MVC layer
  • Mockito: @Mock, @InjectMocks, when().thenReturn() for unit test isolation
  • Automated testing rationale: catch regressions, enable confident refactoring, serve as living documentation
  • @DataJpaTest for repository layer testing with in-memory H2 database

Insights

  • The test pyramid framing is fundamental: most testing value comes from the cheap unit test base, not the expensive E2E apex
  • Spring Boot’s layered test annotations (@WebMvcTest, @DataJpaTest, @SpringBootTest) allow precise control over test context size — a critical performance optimization
  • Mockito’s @InjectMocks is powerful but hides constructor dependencies — can mask design problems

Connections

  • Spring Boot cache preheating article in this vault: the preheating ApplicationRunner code should have integration tests using @SpringBootTest
  • Spring Boot built-in utilities article: testing those utilities requires the same JUnit 5 / Mockito patterns
  • The DRY/abstraction debate (Repeat Yourself): shared test utilities suffer the same wrong-abstraction risk as production code

Raw Excerpt

“測試金字塔的底層是單元測試：快速、隔離、數量最多。中層是整合測試：測試元件間的協作。頂層是端對端測試：最慢但最接近用戶實際體驗。大多數測試價值來自底層的大量單元測試，而非昂貴的頂層測試。”

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