Edit

| transitions from shipping_selected to payment_pending | begin payment | status = payment_pending, expires_at set, inventory reserved | happy path |
| transitions from payment_pending to completed | simulate successful payment | status = completed, order created | happy path |

| transitions from shipping_selected to payment_selected | select payment method | status = payment_selected, expires_at set, inventory reserved | happy path |
| transitions from payment_selected to completed | simulate successful payment | status = completed, order created | happy path |