Regression Testing: Prevent New Bugs When You Update Your App
You land a fix and a different feature breaks. This pattern is common in fast, prompt‑driven builds because one change can touch several places at once. Regression testing protects the basics so you can add features without breaking what people already rely on.
What to protect
- First‑time sign‑up and welcome
- Returning sign‑in and a simple save
- Payments, billing, and any admin action
These are small in number and big in impact, which makes them ideal guards.
Add protection the easy way
Whenever you fix a bug, add a small test for that exact scenario. After a few weeks, your app has a memory of the problems you’ve already solved. When something tries to return, the test flags it before users feel it.
Keep the focus on confidence, not coverage
Numbers can help, but confidence is the goal. A handful of strong regression tests often does more than a large suite that checks trivia. Choose the journeys you would be embarrassed to break and lock those down first.
If you want help setting up a pragmatic regression suite that fits AI‑first development, Spin by fryga can guide you to a small set of tests that delivers outsized confidence.
A practical cadence that sticks
Add one regression test per meaningful bug fix. Review failing tests first each morning. If a failure is a false alarm, tighten the test so it stops crying wolf. If it is real, fix the journey and celebrate that users didn’t have to report it.
What not to include
- Tests for stylistic details (exact spacing, colors) unless your brand demands it
- Flaky tests that sometimes pass and sometimes fail—stability matters more than quantity
Regression testing is about trust. Protect the flows that build it.
Real examples from vibe‑coded apps
- A “Resend code” link fixed a sign‑in edge case, but it accidentally changed the landing page route for returning users. A regression test that asserts “sign‑in → dashboard” caught the change before users did.
- A pricing page added during a marketing push reordered navigation. A small test that checks the order of “Home, Dashboard, Pricing” prevented an accidental swap that would have confused first‑time users.
- An update to the profile form improved copy but removed validation on phone numbers. A regression that creates a user with an invalid number and expects a clear error kept the fix in place across future edits.
Founder FAQs
Do we need a regression test for every bug? No. Write one for bugs that affect revenue, onboarding, or trust. Many cosmetic issues can remain manual until the product stabilizes.
What tools should we use? Choose what your stack already supports. Many teams pair their AI app generation workflow (Cursor, Claude Code, or Lovable) with a lightweight test runner and keep scenarios few and realistic. The tool matters less than consistency.
Will tests slow us down? A handful of well‑chosen regressions speeds you up by preventing emergency fixes after launch. Treat them as insurance that lets you ship more often with fewer surprises.
Case study: protecting a fragile path
An AI‑generated dashboard added a subtle change to navigation that broke “save and return.” A regression test that asserted “after save, land back on the same list with the updated item visible” caught the issue. The fix took one prompt; the test now prevents repeats as the team iterates.