2.3 Test quality verification
2.3 Test quality verification
tests are verified to actually catch bugs, not just exercise lines. Mutation testing (Stryker for TS, Muter for Swift) or equivalent mechanism confirms that tests assert behaviour, not merely execution
Levels
Level 0
No mechanism beyond line coverage
Level 1
PR-review checklist includes "do tests assert behaviour, not just execution?"
Level 2
Mutation testing on critical-path modules (payments, domain protocols, state machines, auth flows) with mutation score target (e.g. >75%); run periodically, not per-PR (scheduling scored under `PL5-signal-driven-tasks`)
Level 3
Surviving mutants auto-create test-improvement tasks; weak-test patterns identified and prevented at template level; mutation score trends tracked over time