Quick Scoop

Regression testing in software testing means re-running previously tested parts of an application after a code change to make sure nothing old broke. It helps confirm that new features, bug fixes, or updates haven’t introduced side effects in existing functionality.

What it does

  • Checks that existing features still work after changes.
  • Catches unintended bugs caused by updates, patches, or enhancements.
  • Often focuses on high-risk or impacted areas first, though teams may run a full suite for bigger releases.

Simple example

If a developer fixes the login page, regression testing might also recheck signup, password reset, and dashboard access to make sure the fix did not break related flows. This is especially important in fast-moving CI/CD teams where frequent releases can accidentally impact stable features.

Why it matters

Regression testing reduces release risk, keeps software stable, and gives teams confidence that changes did not weaken the product. It is a core practice in modern development because even small code edits can create unexpected issues elsewhere.

Types at a glance

  • Selective regression testing: Test only the affected or high-risk areas.
  • Partial regression testing: Check the changed module and nearby components.
  • Complete regression testing: Run the full test suite after major changes.
  • Automated regression testing: Use scripts to run repeated checks faster and more consistently.

If you want, I can also give you a 1-line definition , a real-world example , or interview-style answer.