|Index||-||FAQ - Misc|
The best thing to do is to place an order. You can use these Credit card test numbers.
If the cart is connecting to the gateway properly, the order should be declined with "Bad Card" or "Fraud", etc. The fact that the gateway is actually declining the card means that it is connecting.
The only way to know that EVERYTHING is working perfectly is to place an order with a real credit card. You can always void the transaction in your gateway before the credit card is actually processed.