14. Test edge cases

What it is

Check zero, negative, maximum, missing, malformed, unauthorized, duplicate, and concurrent inputs.

When to use it

Workflow step 14 of 17. Apply before moving to the next decision.

Syntax

14. Test edge cases
Check zero, negative, maximum, missing, malformed, unauthorized, duplicate, and concurrent inputs.

Example

Try amounts -1, 0, 1, maximum, above maximum.
Try another owner, missing account, duplicate key, stale version.
Check that rejected cases leave data unchanged.

Common mistakes

Skipping this decision makes later implementation depend on unstated assumptions.

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