You can use these numbers for testing:

Master Card 5105105105105100 (16) Characters
Master Card 5555555555554444 (16) Characters

Visa 4222222222222 (13) Characters
Visa 4111111111111111 (16) Characters
Visa 4012888888881881 (16) Characters

American Express 378282246310005 (15) Characters
American Express 371449635398431 (15) Characters
Amex Corporate 378734493671000 (15) Characters

Dinners Club 38520000023237 (14) Characters
Dinners Club 30569309025904 (14) Characters

Discover 6011111111111117 (16) Characters
Discover 6011000990139424 (16) Characters
 
JCB 3530111333300000 (16) Characters
JCB 3566002020360505 (16) Characters