thoughtbot/fake_stripe: A Stripe fake so that you can avoid hitting Stripe servers in tests.

fake_stripe spins up a local server that acts like Stripe’s and also serves a fake version of Stripe.js, Stripe’s JavaScript library that allows you to collect your customers’ payment information without ever having it touch your servers. It spins up when you run your feature specs, so that you can test your purchase flow without hitting Stripe’s servers or making any external HTTP requests.

We've also had tests actually hitting the testing sandbox of Stripe, which worked OK most of the time (can be flakey).