I believe that such a card shouldn't work anywhere - even if the terminal didn't validate anything (IIRC they must, and that's likely to be one of the test scen

I believe that such a card shouldn't work anywhere - even if the terminal didn't validate anything (IIRC they must, and that's likely to be one of the test scenarios in the certification process for every new terminal model release) and the issuing bank would accept transactions from that card, a transaction with this card number couldn't get from the terminal to the bank as the network (visa or mastercard) should immediately reject it; all that validation is built in since the earlier days where card numbers may have been passed on manually (taken with an "imprinter" pressing down the embossed numbers through a pad of carbon paper, written down, taken over the phone, etc) with a nontrivial chance of mistakes.