List the edge cases that could break this validation logic
Validation logic that handles the obvious cases well usually fails on the ones nobody thought to try.
- Use it for
- Anyone with validation or input-handling logic who wants to proactively find what breaks it before a user does.
Validation logic tends to get tested against the cases the author already thought of while writing it, which is exactly why it's tested against the wrong set — the cases that actually break validation are the ones that weren't considered in the first place. This prompt looks at the logic specifically for what it doesn't handle, rather than confirming what it does.
When not to use this
For trivial validation with an obviously complete case (a boolean toggle, say), this scrutiny doesn't add much — it's for logic complex or consequential enough that a missed edge case would actually matter.
Did this work?
You have specific, unusual or extreme inputs that plausibly bypass or break the logic, not a generic list of "test nulls and empty strings."
Tested on claude-opus-5. Evidence status is draft; it moves to battle-tested only on recorded runs, never by hand.