Evidence Standards

Use these targets as pressure, not bureaucracy. Raise or lower them based on criticality, repo maturity, runtime cost, and user constraints.

Coverage

• Changed critical decision logic: aim for 100% branch coverage.
• Changed ordinary application code: aim for at least 90% line and branch coverage on touched modules when practical.
• Generated, declarative, UI styling, and framework glue code can use lower coverage if behavior is exercised elsewhere.
• Do not accept coverage that only executes code without assertions tied to behavior.

Mutation Testing

Prioritize mutation testing for:

• Authorization and tenancy logic.
• Financial calculations, billing, quotas, limits, and permissions.
• Parsers, validators, serializers, migrations, and compatibility code.
• Retry, idempotency, reconciliation, and recovery paths.

Triage surviving mutants:

• Add a test when the mutant changes observable behavior.
• Mark equivalent mutants only when the code is genuinely indistinguishable.
• Consider simplifying code when many equivalent or hard-to-kill mutants appear.

Regression Tests

A regression test should:

• Fail against the broken behavior.
• Assert the externally meaningful result.
• Be named around behavior, not implementation details.
• Live close to the layer where the bug escaped.

UAT Coverage

For user-facing features, cover:

• The happy path.
• At least one validation or permission failure.
• The most likely recovery path.
• The workflow state after reload, retry, or navigation when applicable.