use-case-tests - SKILL.md Agent Skill

name: use-case-tests description: Write and run tests for a use case. Use when writing tests for an implemented use case.

Writing Tests for a Use Case

Tests are organized around the use case, not around individual views or layers. A use case may span multiple views, services, and packages — its tests live together so the use case's behaviour can be read and run as a single unit.

Structure

One test class per use case. Name it after the use case: UC001BrowseMovies, UC002BuyTickets, etc. The UC-NNN prefix is the traceability link back to spec/use-cases/use-case-NNN-*.md.
One folder per use case. Place the class (and any supporting fixtures) in src/test/java/com/example/specdriven/usecases/uc001_browse_movies/ (or src/test/frontend/usecases/uc-001-browse-movies/ for tests that must run in the browser). Folder name mirrors the spec filename.
Method names map directly to the spec. Use the segments from the use-case document so a reader can jump from a failing test back to the exact line of spec it covers:
- mainFlow_* — one method per scenario through the Main Flow.
- af1_*, af2_*, … — one method per Alternative Flow, named for its condition.
- br01_*, br02_*, … — one method per Business Rule.

Choosing the test mechanism

The tech is an implementation detail picked per method, not per use case. Within a single use-case class, mix as needed:

Vaadin Browserless Test (SpringBrowserlessTest, @SpringBootTest) for Flow views. Use navigate(ViewClass.class), $(ComponentClass.class), test(component). Use @WithMockUser(roles = "ADMIN") for admin areas, @WithAnonymousUser for access-control checks.
Vitest + React Testing Library for Hilla/React views. Lives under src/test/frontend/usecases/uc-NNN-*/. Mock @BrowserCallable endpoints.
Plain Spring @SpringBootTest when a flow or business rule is best verified directly against a @Service (no UI involved). Prefer testing the service over the @BrowserCallable endpoint.

A use case that combines an admin curation flow with a public browse flow ends up with both browserless and (if applicable) Vitest tests sharing the same UC0xx* name and the same per-use-case folder. They are the same use case's tests, written in whichever mechanism fits each step.

Coverage Requirements

The use case's flows and business rules are the acceptance criteria. There is no separate acceptance-criteria list. Every test method must trace to one of:

Main Flow — at least one mainFlow_* test exercising the happy path end to end.
Alternative Flows — one afN_* test per AF-N, triggering its condition and asserting its branch.
Business Rules — one brNN_* test per BR-N, especially edge cases (limits, validation, error handling).
Postconditions — asserted inside the relevant flow tests.

If a test doesn't map to Main Flow, an AF, or a BR, either it belongs to a different use case or the spec is missing the rule it covers — fix the spec, don't orphan the test.