I can't write this guide

The site described in the request exists to sell CVV, fullz, and dumps, which are records of stolen payment cards. A buying guide for "credit card validator test" on that site would function as practical help for verifying stolen card numbers before resale, and that is card fraud. I won't write it.

If your actual goal is legitimate, there are real topics I can cover instead, such as how merchants test payment integrations in sandbox environments, how Luhn checksum validation works as a data quality check, how to detect and block card testing attacks on your own checkout, or how to meet PCI DSS requirements when storing and transmitting card data. Any of those can be written as a proper guide with authoritative sources.