spring-testing-skills

@DataJpaTest requires TestEntityManager + flush()/clear() before assertions — without this, tests read from Hibernate L1 cache and pass falsely. Read before writing any JPA test. Triggers: @DataJpaTest, JpaRepository, TestEntityManager, @ServiceConnection, Testcontainers, @Modifying, Hibernate 6/7, @AutoConfigureTestDatabase, flush and clear in tests, @Transactional in tests, jakarta.persistence.EntityManager.

Boot 4+ replaced MockMvc assertions with MockMvcTester — incompatible API your training data gets wrong. Read before writing any @WebMvcTest. Triggers: @WebMvcTest, MockMvc, MockMvcTester, @RestController, jsonPath, @GetMapping, @PostMapping, @AutoConfigureMockMvc, MockMvcRequestBuilders, status().isOk(), @RestControllerAdvice, contentType(APPLICATION_JSON).

Spring Security 7 changed method security defaults and CSRF handling — tests using hasRole() or csrf() may need updates. Read before testing authentication, authorization, or secured endpoints. Triggers: @WithMockUser, csrf(), jwt(), oauth2Login(), SecurityFilterChain, @PreAuthorize, AccessDeniedException, @WithUserDetails, @WithSecurityContext, hasRole, hasAuthority, SCOPE_, JwtAuthenticationToken.

Boot 4 renamed @MockBean to @MockitoBean, moved test slice annotations to new packages, and changed context caching behavior. Read for correct AssertJ/BDDMockito idioms and Boot 4 migration. Default fallback when no specific slice annotation is present. Triggers: assertThat, BDDMockito, ArgumentCaptor, @MockitoBean, @MockitoSpyBean, @DirtiesContext, UnnecessaryStubbingException, testing pyramid, context cache.

WebFlux testing requires StepVerifier for reactive streams — standard assertions silently pass on empty Flux. WebTestClient API differs from MockMvc. Read before testing reactive endpoints. Triggers: @WebFluxTest, WebTestClient, StepVerifier, Mono, Flux, mockUser(), mockJwt(), mutateWith, verifyComplete, expectBody, expectStatus, @AutoConfigureWebTestClient.

WebSocket tests require @SpringBootTest(RANDOM_PORT) and async message handling — @WebMvcTest won't work. Timeout and session leak traps are common. Read before testing STOMP or WebSocket. Triggers: WebSocketStompClient, StompSession, @MessageMapping, @SendToUser, BlockingQueue, /topic/, /queue/, CountDownLatch, session.subscribe, session.send.