What is Regression Testing?

What is regression testing?

Regression testing is the process of verifying that changes to a software system — new features, bug fixes, refactoring, or dependency updates — haven't broken existing functionality that was previously working. The term "regression" refers to something that worked before and now doesn't: a step backwards in quality.

Regression testing is one of the most critical activities in software QA, and one of the most commonly underinvested in. Every code change is a potential regression — every bug fix touches real code that real features depend on.

Why regression testing matters

Without systematic regression testing, bugs accumulate silently. A developer fixes a bug in the checkout flow — and inadvertently breaks the discount code application that shared the same function. A designer updates a shared component — and the responsive layout on the pricing page breaks. Without regression coverage, both bugs ship to users.

Types of regression testing

Complete regression testing

Re-run the entire test suite after every change. Guarantees maximum coverage but is time-consuming. Practical for small suites or automated suites that run fast.

Selective regression testing

Run only the subset of tests most likely to be affected by the specific change. Requires understanding the code impact radius — which areas of the application are touched by this change?

Progressive regression testing

Add new test cases with every bug fix. Over time, your suite becomes a comprehensive regression guard covering all known failure modes.

Automated vs. manual regression testing

Regression testing is the highest-value use case for automation. The tests don't change (they're verifying existing behaviour), they need to run frequently, and speed matters. Playwright, Cypress, or Selenium are all effective for automated regression suites.

Manual regression testing is valuable for areas that are hard to automate — complex UI interactions, visual consistency, UX-layer checks — but it doesn't scale. As your product grows, you need automated coverage for the core regression risk.

Building a regression test suite

1. Identify your highest-risk areas — core user journeys, revenue-critical flows, complex business logic
2. Write automated tests for every critical path
3. With every bug fix, add a test that would have caught the bug
4. Run the full automated suite on every pull request and before every deployment
5. Review and prune the suite quarterly — remove tests that are no longer relevant

RedQA's test automation service includes building and maintaining regression suites with Playwright. Get in touch to discuss your needs.