01What regression catches
When you ship a change — a refactor, a new feature, a dependency upgrade — something previously working might break unexpectedly. Regression testing re-runs the test cases most likely to expose that.
Common triggers:
- Pre-release before a major version
- After a refactor or significant dependency upgrade
- After an infrastructure change
- When a defect fix touches shared code
02Scoping a regression run
A useful scoping rubric:
- All P0 (critical-path) cases — every release.
- High-priority cases in areas touched by recent changes — change-impact-driven.
- Cases that recently failed — confirm the fix held.
- A rotating sample of medium-priority cases — to keep the long tail covered without retesting everything.
03Manual vs automated regression
If you have automation, it should carry the bulk of regression — that's its strongest use case. Manual regression covers what automation can't (or won't) cover: visual checks, integrations, mobile-on-real-devices, accessibility.
04Related
05Frequently asked questions
Do I have to re-run every test on every release?
No. A full regression suite on every release is impractical for most teams. Risk-based regression — focusing on high-priority cases plus areas touched by recent changes — is the usual compromise.
How is regression different from smoke testing?
Smoke testing is a tiny subset that confirms basic functionality works at all. Regression is broader, designed to catch unintended breakage in previously-working features. See smoke vs sanity testing.