apavithraa/springboot-architecture
Skills for creating, testing, reviewing, migrating and guarding Spring Boot 4 projects with Java 25: project scaffolding with architecture patterns, Boot 4 test templates, code review, Boot 3 to 4 migration, and a team harness of build gates and agent hooks.
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boot4-test-toolkit.mdskills/code-reviewer/references/testing/
Spring Boot 4 Test Toolkit
Boot 4 split the test support into modules, and agents most often get these imports wrong. Packages were checked against the Boot 4.1.1 jars on Maven Central (October 2026).
Imports
| Annotation / class | Package | Module |
|---|---|---|
@SpringBootTest, @TestConfiguration | org.springframework.boot.test.context | spring-boot-test |
@WebMvcTest, @AutoConfigureMockMvc | org.springframework.boot.webmvc.test.autoconfigure | spring-boot-webmvc-test |
@DataJpaTest | org.springframework.boot.data.jpa.test.autoconfigure | spring-boot-data-jpa-test |
TestEntityManager | org.springframework.boot.jpa.test.autoconfigure | spring-boot-jpa-test |
@JdbcTest, @AutoConfigureTestDatabase | org.springframework.boot.jdbc.test.autoconfigure | spring-boot-jdbc-test |
@JsonTest | org.springframework.boot.test.autoconfigure.json | spring-boot-test-autoconfigure |
@RestClientTest | org.springframework.boot.restclient.test.autoconfigure | spring-boot-restclient-test |
@AutoConfigureRestTestClient | org.springframework.boot.resttestclient.autoconfigure | spring-boot-resttestclient |
@ServiceConnection | org.springframework.boot.testcontainers.service.connection | spring-boot-testcontainers |
MockMvcTester | org.springframework.test.web.servlet.assertj | spring-test |
RestTestClient | org.springframework.test.web.servlet.client | spring-test |
@MockitoBean, @MockitoSpyBean | org.springframework.test.context.bean.override.mockito | spring-test |
@TestBean | org.springframework.test.context.bean.override.convention | spring-test |
DynamicPropertyRegistrar, @Sql | org.springframework.test.context, …context.jdbc | spring-test |
PostgreSQLContainer (Testcontainers 2) | org.testcontainers.postgresql | testcontainers-postgresql |
KafkaContainer (Testcontainers 2) | org.testcontainers.kafka | testcontainers-kafka |
KafkaConnectionDetails | org.springframework.boot.kafka.autoconfigure | spring-boot-kafka |
@EnableWireMock, @ConfigureWireMock, @InjectWireMock | org.wiremock.spring | org.wiremock.integrations:wiremock-spring-boot 4.4.3 (not managed by Boot) |
@Retryable, @EnableResilientMethods | org.springframework.resilience.annotation | spring-context |
Test starters per technology: spring-boot-starter-webmvc-test, spring-boot-starter-data-jpa-test, spring-boot-starter-restclient-test, spring-boot-starter-kafka-test, spring-boot-starter-security-test, all with <scope>test</scope>. Testcontainers support is spring-boot-testcontainers; there is no -starter- for it.
Versions Boot 4.1.1 manages: JUnit Jupiter 6.0.3, Mockito 5.23.0, AssertJ 3.27.7, Awaitility 4.3.0, Testcontainers 2.0.5. Don't pin them yourself.
Boot 4 changes agents miss
@MockBeanand@SpyBeanare gone: use@MockitoBean,@MockitoSpyBean.TestRestTemplateis on its way out: useRestTestClient.@SpringBootTestno longer auto-configures HTTP test clients. Add@AutoConfigureRestTestClientor@AutoConfigureMockMvc.RestTestClientsends a request body with.body(object)..bodyValue(...)isWebTestClient's method and does not compile onRestTestClient.- The Testcontainers 2 module classes take no type parameter:
PostgreSQLContainer, notPostgreSQLContainer<?>.GenericContainer<?>keeps it. - Spring Framework 7 pauses cached contexts between uses, so scheduled tasks and listeners in an idle cached context no longer interfere with other tests.
- One shared container configuration for the whole suite:
../../../writing-springboot-tests/assets/testcontainers-configuration.java.
PIT
Use PIT before breaking code by hand, for any class with plain unit tests. In a trial on an OrderService (39 mutants), PIT took 6 seconds. Breaking each line of the same class by hand, through Maven and a container per run, did not finish in 10 minutes.
Add ../../../writing-springboot-tests/assets/pitest-plugin.xml (pitest-maven 1.30.1, pitest-junit5-plugin 1.2.3, checked October 2026), then run it for one class:
./mvnw test-compile org.pitest:pitest-maven:mutationCoverage \
-DtargetClasses=com.example.orders.domain.OrderService \
-DtargetTests='com.example.orders.domain.*Test'The report is in target/pit-reports/index.html. Gradle: the info.solidsoft.pitest plugin with junit5PluginVersion set; the parameters have the same names.
- Start with unit and slice tests. PIT runs the tests once per mutant, so tests that start containers make it very slow.
- In a test with a cached Spring context, mutants in constructors and
@PostConstructcode survive however good the tests are: each bean is built once. A surviving "Removed assignment to member variable" there is this artifact, not a gap. - Don't chase 100%. Chase survivors in the logic the change is about, and name equivalent mutants.