Everytime I want to make a test purchase in Test Mode I have to search for this documentation page in order to pull up these instructions:
4242 4242 4242 4242 to test a successful payment
4000 0000 0000 9995 to test a declined payment
4000 0027 6000 3184 to test a payment with 3DS authentication
For the expiration date, use any future date (such as 12/34) and for the CVC, use any 3-digit value.
It would be much nicer to have the checkout in Test Mode automatically fill in those details, or suggest the correct information when the card number input is focused.
Alternatively, add a link to this page if Test Mode is enabled