Testing

Testing Skill

Testing guidance focused on durable behavior and maintainable feedback loops.

Core Principles

• Tests protect durable contracts, invariants, and failure modes.
• Prefer tests that still matter after refactors, removals, and package moves.
• Coverage informs risk; it is not a target to game.

Choose the Right Test Level

• Unit tests: deterministic domain logic, pure transformations, validation rules.
• Integration tests: seams between transport, domain, storage, and adapters.
• End-to-end tests: critical user/system paths only.
• During architecture-first refactors, favor seam/integration coverage around stable contracts before cutover.

Test-First Guidance (Not Ceremony)

• Prefer test-first when it clarifies behavior or de-risks implementation.
• For large refactors or testability seam setup, it is acceptable to reshape code first, then add or adjust tests before declaring the change done.
• Do not create ceremonial failing tests for behavior intentionally removed.
• When behavior is removed, delete stale tests and replace them only with tests for the new intended contract.

Durable Assertion Heuristics

• Start with a user-visible contract: what should render, enable, redirect, or block.
• Prefer positive assertions (contains, state transitions, status, links) over absence assertions.
• Use negative assertions only for explicit invariants (security/privacy/protocol/mutual exclusion).
• Every allowed negative assertion should include an adjacent // Invariant: ... rationale.

Example:

• Weak assertion: "response does not contain class foo."
• Strong assertion: "HTMX response returns fragment content and does not include a full HTML document wrapper (Invariant: protocol contract)."

Coverage Guardrails

• Use make cover and make cover-critical-domain only when you need focused standalone coverage diagnostics outside the normal verification workflow.
• If coverage drops, explain whether risk changed and add targeted tests when needed.
• If you introduce generated outputs, update COVER_EXCLUDE_REGEX in Makefile so coverage reflects hand-written code.

Verification

• Use the public verification surface from docs/running/verification.md:
  • make test during normal implementation
  • make smoke when runtime paths need quick feedback
  • make check before pushing or updating a PR
• Do not run make cover* in parallel with make check; make check already generates the shared coverage artifacts.
• When a verification command is running in the background, inspect .tmp/test-status/ instead of repeatedly re-running or blindly polling the process.
• Use .tmp/test-status/test/status.json for make test.
• Use .tmp/test-status/smoke/status.json for overall make smoke stage progress.
• Use .tmp/test-status/smoke/integration/status.json and .tmp/test-status/smoke/scenario/status.json for lane-specific make smoke progress.
• Use .tmp/test-status/check/status.json for make check stage progress.
• If make check is in check-runtime, read .tmp/test-status/check-runtime/scenario/status.json.
• If make check is in check-coverage, read .tmp/test-status/cover/status.json and the nested shard status files under .tmp/test-status/cover/.
• Treat state, current_stage, current_package, current_test, packages_completed, packages_running, updated_at_utc, and last_event_at_utc as the primary fields for liveness and progress.
• If a command cannot run locally, report why and what risk remains.

Removal Policy

• Do not preserve tests that only assert a removed feature, path, or section stays gone.
• If no durable invariant remains after a removal, delete the stale test.
• If a negative assertion must remain, add an adjacent Invariant: rationale.

Testability

See docs/architecture/policy/testing-policy.md for constructor, dependency injection, and fake-oriented testability guidance.

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