01The simplest definition
- Test scenario: what behaviour we want to verify
- Test case: how we verify it, step by step
A scenario can spawn many cases. "User sign-up flow" is a scenario; the cases under it might include valid email, invalid email format, password too short, duplicate email, verification link expiry, verification link tampering, and so on.
02When you'd use one vs the other
- Use scenarios when discussing test plans with non-QA stakeholders, or when sketching coverage before writing detailed cases.
- Use cases when actually executing testing — they're the unit you record results against in a test run.
03Don't conflate them
The mistake is calling a scenario a "case" and writing one giant unstructured test that fails for ambiguous reasons. The fix is to break it into several small cases, each with one clear pass/fail outcome.
04Related
05Frequently asked questions
Should I write scenarios or cases?
Both. Scenarios describe end-to-end behaviour and read like requirements. Cases drill into specific checks that can be executed unambiguously.
How granular should test cases be?
One pass/fail outcome per case. If a case has three independent things that could fail separately, it should probably be three cases.