spring-boot-testing

Select a Spring Boot test slice by matching it to your component: @WebMvcTest for controllers, @DataJpaTest for the data layer, @RestClientTest for REST clients, and @JsonTest for JSON processing to ensure fast, deterministic tests.

Use a full @SpringBootTest when you need to test the complete application context and integration across multiple layers, whereas test slices are better for isolated, fast unit-style tests targeting specific components like controllers or repositories.

Test Spring Boot controllers by applying the @WebMvcTest slice to isolate the web layer, then use MockMvc or MockMvcTester to simulate HTTP requests and AssertJ to write fluent, expressive assertions on the response state and body.

Yes, this Spring Boot testing guidance defines best-practice patterns using JUnit 6 and AssertJ, and it incorporates Testcontainers where appropriate for integration-style tests requiring real external dependencies like databases.

The best way to migrate Spring Boot tests is to follow the provided decision matrix and migration guidance, replacing broad @SpringBootTest annotations with narrow slices like @DataJpaTest or @RestClientTest to dramatically improve test speed and reliability.

Spring Boot integration tests run slowly when loading the full application context unnecessarily; fix this by switching to targeted test slices like @WebMvcTest or @JsonTest to load only the specific components required for the test.