NULL Gateway
585 BDo you do frequent testing of WHMCS product provisioning and all things related such as invoice handling and addon provisioning? Want a seemless testing process without the actual exchange of currency? Use this null gateway module. You set it up like any other payment gateway, apply it only to your test products and you can go through the process of testing payment processing without actually making payments. It will take a standard test credit card number and return a successful transaction. This allows WHMCS to continue with the automated processes that happen when a payment is received.
http://www.paypalobjects.com/en_US/vhelp/paypalmanager_help/credit_card_numbers.htm