In developer mode, I've tested credit cards that usually give the
correct response (invalid expiration date, invalid card number,
accepted, etc.). However, when I enter in my credit card and
intentionally put in something incorrect (such as wrong yea...
An expired card works; I meant that I'd enter in the incorrect
expiration date (2023 instead of 2024, for example) and it would still
go through, or if I test a card that has no more credit available and
still gets "charged".