JUnit 5 Mechanics for Spring Boot Services

Own the mechanical half of testing: how a test is shaped, named, parameterized, grouped, extended, and executed. A deterministic, isolated, self describing test can fail in a build and tell you what broke. An order dependent, clock dependent test named test3 cannot.

When to use

• Adding or reviewing a @Test method, a test class, or a suite, and choosing between a plain test, a parameterized test, and a @Nested group.
• Replacing a flaky Thread.sleep, a hard-coded date, or an order dependent assertion, or configuring surefire and failsafe execution.
• Writing AssertJ assertions, soft assertions, assumptions, or @Tag suite boundaries.

When not to use

• Mock, spy, and stub design belongs to spring-boot-mockito.
• Real database, Redis, or broker dependencies belong to spring-boot-testcontainers.
• Choosing between a plain test, a slice test, and a full context test belongs to spring-boot-integration-testing.
• Pipeline ordering and test stage gating belong to spring-boot-ci-cd.
• Constraint semantics on production payloads belong to spring-boot-validation.

Ownership and sibling boundaries