spring-boot-testing

Spring Boot 4 replaces @MockBean with @MockitoBean and @SpyBean with @MockitoSpyBean. Update your test class annotations, then re-run your unit and slice tests. The Skill provides migration patterns for @WebMvcTest, @DataJpaTest, and security-testing scenarios with working examples and troubleshooting references.

Slice tests target specific layers—@WebMvcTest for controllers, @DataJpaTest for repositories—loading only relevant beans and running faster than full integration tests. Use them to isolate and verify single components with mocked dependencies before running end-to-end tests.

@ServiceConnection automatically wires Docker containers into your Spring context without manual configuration. Declare a @ServiceConnection-annotated container field, and Boot 4 injects connection properties. This simplifies integration tests against real databases, message brokers, and services.

Yes. Spring Boot 4 slice tests support @WithMockUser for role-based testing and custom JWT scenarios in @WebMvcTest. The Skill covers both approaches, including MockMvcTester and WebTestClient assertion tools for verifying security filters and endpoint access control.

MockMvcTester is the newer, fluent API for servlet-based @WebMvcTest slices with improved assertion syntax. WebTestClient handles reactive and async endpoints. Choose based on your application type—servlet stack or reactive stack—and Boot 4 slice test context.

Modulith's Scenario API lets you verify module interactions and event flows without mocking. Boot 4 slice tests work with Scenario for isolated module verification. The Skill shows end-to-end workflows combining slice tests, @MockitoBean, and Scenario-based assertions.