Skip to content
Appsierra
QA & Testing

What is Regression Testing?

By the Appsierra Knowledge Desk
Reviewed by senior engineers · Updated September 2026

Regression testing is the practice of re-running existing test cases after a code change — a new feature, bug fix, or configuration update — to confirm that previously working functionality still behaves correctly. It catches unintended side effects (regressions) before they reach users, and is usually automated so a full suite can run on every build without slowing delivery.

Also called regression test
Get a free QA audit →
AT A GLANCE
Term
Regression Testing
Category
QA & Testing
Sections
3
Questions answered
4
Updated
September 2026
Part of the Appsierra software testing & AI glossary.
GET THIS SCOPED — 20 SECONDS

Want this applied to your codebase?

Tell us the shape of it. A senior engineer replies with a scoped plan and an honest cost range — not a sales script.

One field to start. No sales call required.
Prefer to talk first? Book a 30-minute call.

Why is regression testing important?

Every code change risks breaking something that already worked. Regression testing is the safety net that catches those breakages early, when they are cheap to fix, instead of in production where they damage trust and revenue.

Without it, teams slow down: developers fear that each change might silently break a distant part of the system. A reliable regression suite gives teams the confidence to ship frequently.

When should you run regression tests?

Run regression tests after every meaningful code change: new features, bug fixes, dependency upgrades, and configuration changes. In a mature pipeline the suite runs automatically on every pull request and before every release.

Because full regression suites can grow large, teams use risk-based and impact-based selection to run the most relevant tests first, with the complete suite running nightly or pre-release.

How Appsierra reduces regression cycles

Appsierra has cut multi-day regression cycles to hours for clients by automating high-value regression paths and running them continuously in CI/CD, with senior engineers reproducing every failure before it is reported. We prioritise the suite by risk so the fastest, most relevant feedback reaches developers first.

To shorten your regression cycle, explore our regression testing and automation testing services.

Frequently asked questions

What is regression testing in simple terms?
Regression testing means re-checking features that already worked after you change the code, to make sure the change didn't accidentally break them.
What is the difference between regression testing and retesting?
Retesting verifies that a specific known defect has been fixed. Regression testing checks that the fix or change didn't break other, previously working functionality.
Should regression testing be automated?
Usually yes. Regression suites are repetitive and run often, which makes them ideal for automation. Automating them lets the full suite run on every build without slowing the team.
How often should regression testing run?
Ideally on every code change in CI/CD, with risk-based selection for fast feedback and the full suite running nightly or before each release.
No-risk start

Need help with Regression Testing?

Appsierra's expert-supervised QA and AI engineering pods put regression testing to work for your team. Talk to us about your goals and we'll map a practical, de-risked path forward.

Get a free QA audit →
EXPLORE
Free ROI calculator What QA & dev cost Compare delivery models Hire a vetted pod Expert answers
GET THIS SCOPED — 20 SECONDS

Need this applied to your codebase?

Tell us the shape of it. A senior engineer replies with a scoped plan and an honest cost range — not a sales script.

One field to start. No sales call required.
Prefer to talk first? Book a 30-minute call.
Vetted pods, productive in 7 days
Senior-reviewed pods · live in ~7 days · cancel anytime
Run the ROI numbers