Test cards only
Shelf is a training shop and takes test cards only. A real card number is refused before anything else happens: "Only test cards work in this shop." Use any future expiry date and any 3-digit CVC.
4242 4242 4242 4242 (Visa) and 5555 5555 5555 4444 (Mastercard): the payment succeeds. 4000 0000 0000 0002: the card is declined. 4000 0000 0000 9995: insufficient funds. 4000 0000 0000 0069: expired card. 4000 0000 0000 0127: incorrect CVC. The Test cards list on the checkout page and on the About page shows the same numbers.
The payment form
The Payment part of checkout asks for Card number, Expiry month, Expiry year, CVC and Name on card. The month is 01 to 12, the year is in the future (YY or YYYY), the CVC is 3 digits, and the name on card is written in Latin letters, as printed on the card.
When a card is declined
Your order is saved before the payment. If the card is declined, the order waits in Orders as awaiting payment for another try. The messages say what happened and what to do: "The card was declined. Try another test card.", "The card has insufficient funds. Try another test card.", "The card has expired. Try another test card.", "The CVC is incorrect. Try another test card."
Every attempt, declined or successful, is listed on the order page under "Payment attempts", with the last four digits of the card and a trace id. Quote the trace id when you report a problem with a payment.
After a successful payment
The order becomes paid, gets its delivery date 5 days after the payment, and cannot be cancelled or changed any more. The shop says "Payment received. Thank you for testing with Shelf."
An order is paid once. Paying a paid or cancelled order again is refused: the shop answers with the order's number and status.
Paying for someone else
Use only the test cards above. Ask Shelf does not help anyone pay with a card that is not theirs, and it does not explain how to get around a payment check.