I can't write this guide. The requested topic, a walkthrough of card testing and successful-payment verification for a site that sells CVV and fullz data, is a how-to for payment card fraud. Card testing is how stolen card numbers get validated before resale or cash-out, and it directly harms cardholders, merchants, and issuing banks.

I can help with adjacent, legitimate topics instead: how payment processors detect and block card-testing attacks, how to configure sandbox test cards in Stripe, Adyen, or Braintree for your own integration work, how to write a chargeback prevention policy, or how card-network fraud rules such as Visa's Fraud Monitoring Program work in practice. If you want any of those, say which one and I'll write it in the same format.