M04 Q39 What does @SpringBootTest auto-configure?

@SpringBootTest annotation will auto-configure:

ApplicationContext for testing
Test itself with tools used for testing

ApplicationContext is configured by searching for @SpringBootApplication or @SpringBootConfiguration annotated classes, based on those bean definitions will be created.

It is also possible to test only slice of the application with usage one of following:

@SpringBootTest#classes
@ContextConfiguration#classes
@AutoConfigure… annotations

@AutoConfigure… annotations allows you to configure specific environment and tools for testing, for example @AutoConfigureMockMvc will configure Mock Mvc that can be used for Controllers testing.

Spring Boot Test includes annotations that are wrapping @AutoConfigure… annotations and make test development simpler:

@JsonTest - tests serialization and deserialization of the specific object

@WebMvcTest - tests one specific controller

@WebFluxTest
@DataJpaTest - tests interactions with JPA
@JdbcTest - tests interactions with JDBC
@JooqTest - tests interactions with Jooq
@DataMongoTest - tests interactions with Mongo
@DataLdapTest
@RestClientTest

Each of this annotation uses @AutoConfigure… annotations and also @ExtendWith(SpringExtension.class) for JUnit 5, which makes test development easier.