Stop 10 · Testing & User AcceptanceTopics · 6/8

Regression Testing Basics

In short

The team fixed the refund bug. Great. But did the fix quietly break invoices? Regression testing checks that what worked yesterday still works today, after every change.

Verifying that a new change hasn't broken previously working functionality — a BA's role is often ensuring critical business workflows are included in the regression test scope, not just the new feature.

The purple blob turns a bathroom tap with a wrench in one hand, with a geyser on the wall behind it.

Think of it like this

After the plumber leaves

The plumber fixes the leaking kitchen tap. Before he goes, you check the bathroom tap, the geyser and the flush, because they're all on the same pipes. Fixing one thing can disturb another. Checking the rest is regression testing.

Watch it happen

A change to payments: what else to retest?

Payment change

Directly hit

Linked flows

Checkout

Refunds

Invoices

Sales reports

1/5Developers changed how card payments are processed. What could this affect?

The big ideas

What you need to know

Retest what worked

Regression testing reruns tests on existing features after a change, to catch unintended side effects.

A regression pack

Teams keep a set of key tests to rerun every release. Many automate it so it runs in minutes.

Risk-based selection

You can't retest everything every time. Focus on areas linked to the change and on business-critical flows.

BA picks the critical paths

You know which flows the business can't live without, like month-end billing. Make sure they're always covered.

Save yourself the pain

Common mistakes

Oops

Testing only the new feature before release.

Do this instead

Always include a regression run on related and business-critical flows.

Oops

Keeping a regression pack that's never updated.

Do this instead

Add tests for every important bug fixed and remove ones for retired features.

Your mission

Build a mini regression pack

~25 min

Quick check

A small change was made to the discount code feature. Which regression tests matter most?

Go deeper

1Identify 5 critical business workflows that should always be included in regression testing.
2Learn why regression testing scope tends to grow over time as a product matures.
3Understand why skipping regression testing to save time is a common, risky shortcut.