Pure-reference catalog of test-code conventions: AAA structure (Arrange / Act / Assert), per-test single-responsibility, descriptive naming (`{sut}_{scenario}_{expected}`), assertion specificity, mocking rationale (state vs behavior, fake vs mock), fixture-coupling rules, and the magic-number / hard-coded-string anti-patterns; the E2E selector-priority and web-first-assertion conventions live in references/. Use as the shared rule book a test-code review cites back to, or as onboarding for what makes a test code-reviewable; to score a test's quality on weighted axes use test-design-scorecard, and for setup/teardown isolation specifically use test-isolation-patterns.