Regression Testing

<default_to_action> When verifying changes don't break existing functionality:

1. ANALYZE what changed (git diff, impact analysis)
2. SELECT tests based on change + risk (not everything)
3. RUN in priority order (smoke → selective → full)
4. OPTIMIZE execution (parallel, sharding)
5. MONITOR suite health (flakiness, execution time)

Quick Regression Strategy:

• Per-commit: Smoke + changed code tests (5-10 min)
• Nightly: Extended regression (30-60 min)
• Pre-release: Full regression (2-4 hours)