Instruction file imported from Abhiram1106/CodeJudgeX (.cursor/rules/testing.mdc). Copyright stays with the author.

Testing Rules — CodeJudgeX

Backend (JUnit 5 + Spring Boot Test)

• Unit tests: no Spring context, no IO, no database — test service/mapper logic in isolation
• Integration tests: use @SpringBootTest with a real PostgreSQL container (Testcontainers)
• Every bug fix gets a regression test — add it before closing the task
• One assertion per test where practical; one reason to fail per test always
• No shared mutable state between tests — use @BeforeEach to reset
• Mock at HTTP/queue boundaries (MockMvc, MockRabbitMQ) — never mock the class under test
• Test class naming: {ClassName}Test for unit, {ClassName}IT for integration

Frontend (Vitest + Testing Library)

• Query by role, label, or text — never by test ID unless no semantic alternative exists
• No snapshot tests for interactive components — they catch nothing useful and break constantly
• Test user behaviour, not implementation details — never assert on internal state
• Every API call in tests must use msw (Mock Service Worker) handlers — never mock axios directly
• Flaky tests are bugs — quarantine immediately, fix or delete. Never retry-to-green.

Evaluation pipeline testing

• The evaluation worker must be tested with a real Judge0 CE instance (Docker Compose) in CI
• Never mock Judge0 responses for integration tests — the actual sandbox behaviour is the contract
• Test all terminal verdict types: ACCEPTED, WRONG_ANSWER, TIME_LIMIT_EXCEEDED, RUNTIME_ERROR, COMPILATION_ERROR

Coverage policy

• Track coverage on backend/src/main/java/com/codejudgex/{auth,submission,evaluation,leaderboard}/
• No coverage targets enforced — meaningful tests over line-coverage theatre