Try to fool it
Ten ways people try to cheat a stranger deal. Each one runs now, against the same code a live deal uses. The result comes from what the code did, with the rule that stopped it and the test that proves it.
Judge mode: these attacks run through Settle Link's real server code in a throwaway store. PayPal is stood in, so nothing reaches PayPal and no money moves.
Ten ways people try to cheat a stranger deal. Each one runs now, against the same code a live deal uses. The result comes from what the code did, with the rule that stopped it and the test that proves it.