How can I test the checkout and customer login area?
Unfortunately, at this point there is no way for you to test or preview the full flow of the checkout and customer login area and it's functionality. Please vote on it here though.
However, there is a nice little workaround that solves this issue.
What you can do is go through checkout process yourself to preview it, and then after refund yourself through the Stripe dashboard afterwards.
We recommend creating a new account using a separate email for testing. Please make sure you logout of the admin first to see the full checkout process. A quick way of doing this is using Incognito mode on Chrome.