spring-boot-test

Spring Boot Test Engine

Naming Conventions

• Name test methods using the pattern <operation>_when<Condition>_should<ExpectedResult> (e.g., transfer_whenSufficientBalance_shouldTransferSuccessfully).

Rules

• Use spring-boot-java-style.mdc as the cross-cutting baseline for repeated string-literal extraction in test classes.
• Use layer-appropriate test slices: @WebMvcTest(ControllerClass.class) for HTTP contract tests, @JdbcTest for repository tests, @ExtendWith(MockitoExtension.class) for unit tests, @SpringBootTest for full integration tests.
• Prefer narrow test slices (@WebMvcTest, @JdbcTest) over @SpringBootTest for single-layer tests.
• Import @WebMvcTest from org.springframework.boot.webmvc.test.autoconfigure.WebMvcTest (module spring-boot-webmvc-test).
• Import @JdbcTest from org.springframework.boot.jdbc.test.autoconfigure.JdbcTest (module spring-boot-jdbc-test).
• Import @MockitoBean from org.springframework.test.context.bean.override.mockito.MockitoBean.
• Use Spring Boot 4.x test import paths only.
• Do not import @MockBean or annotations from org.springframework.boot.test.mock.mockito / org.springframework.boot.test.autoconfigure.web.servlet.
• Use MockMvcTester (from org.springframework.test.web.servlet.assertj.MockMvcTester) for AssertJ-native controller assertions in @WebMvcTest slices.
• Use RestTestClient (from org.springframework.test.web.servlet.client.RestTestClient, module spring-boot-resttestclient) for testing REST endpoints against a running server in @SpringBootTest(webEnvironment = RANDOM_PORT) tests.
• For @WebMvcTest classes that serialize JSON fixtures, explicitly enable JSON auto-configuration in the test slice before autowiring ObjectMapper.
• For @WebMvcTest, serialize request and response fixtures using the slice-configured ObjectMapper (or JacksonTester).
• Handcraft JSON strings only for intentionally malformed-payload tests.
• For @WebMvcTest classes that invoke controller methods with Pageable parameters, enable Spring Data web argument-resolver auto-configuration with @ImportAutoConfiguration(SpringDataWebAutoConfiguration.class).
• Confirm PageableHandlerMethodArgumentResolver is active in those @WebMvcTest classes.
• Execute at least one request that includes page, size, and sort query parameters in those @WebMvcTest classes.
• When a controller under test depends on a *LogMessages component in @WebMvcTest, declare a matching @MockitoBean for that concrete *LogMessages type.
• If tests fail because the required SGBD runtime is unavailable, classify the failure as an environment blocker, skip only the database-coupled test scope, continue non-database tests, and report the concrete failure signal.
• Keep database-coupled tests enabled when the required SGBD runtime is healthy and reachable.
• When @JdbcTest requires a custom repository implementation, explicitly @Import({RepositoryImpl.class, JdbcConfig.class}) and ensure JdbcClient is a @Bean.
• Declare @Configuration classes imported via @Import as public when required by the test slice; this overrides architecture package-private for that class only.
• Place imported @Configuration classes in a scannable package.
• For security-chain tests with @SpringBootTest, manually configure MockMvc with webAppContextSetup(context).apply(springSecurity()).build().
• Use static imports from org.springframework.security.test.web.servlet.setup.SecurityMockMvcConfigurers and org.springframework.test.web.servlet.setup.MockMvcBuilders.
• Apply @Transactional to database-touching integration tests for rollback isolation.
• Use builder methods or dedicated factory methods for test data construction.
• Use java.time.Month enum constants for static date fixtures in LocalDate.of calls.
• Keep service tests focused on business rules and edge cases.
• Keep response-structure assertions explicit for API tests.
• Assert success and failure paths for each changed behavior.
• Write at minimum one happy-path test and one failure-path test for each public service method and each REST controller endpoint.
• Add governance tests when architecture invariants require enforcement.
• Use AssertJ (assertThat(...)) for all test assertions.
• Remove unused @MockitoBean stubs.
• Run tests under development or production; no dedicated test profile exists.
• Use inline @Bean methods or environment variable overrides in test classes instead of a dedicated test profile file.
• Add @AutoConfigureTestDatabase(replace=NONE) only when explicitly targeting a real external datasource.