Testing with mock credit card numbers

My coworker Milind Pandit sent me the following link the other day:

http://www.giveusallyourmoney.com/

It appears that phishers have resorted to honesty by just simply telling you truth
about what they want from you. Pure genius!

I'm not sure if this is real or not because when I put in a Visa card number I
get the following error AND success message:

Warning: fopen(/var/guaym/creditcards.txt): failed to open
stream: No such file or directory in /var/www/giveusallyourmoney.com/taketheirmoney.php
on line 9
error taking your money.

Thank you, Brent Strange ,for giving us all your money!

No, I wasn't stupid enough to put in my Visa card number... I used my wife's
instead. Okay, okay, I didn't use hers either. Give me a little credit. You
can create test credit card numbers on your own using MOD 10. How do I know this?
No, I'm not an evil hacker. I once was part of a payments solution group at Intel (TranSync)
and I had to test various card types. Graham King has a great little article on credit
card test number generation here.