Plain HTML. No Phoenix, no framework, no build step. It exercises only the browser half
of Hosted Checkout — checkout.min.js, Checkout.configure(),
and the display method — so a failure here is the gateway integration itself rather than
anything in our application.
INITIATE_CHECKOUT request in the internal Postman collection, or from
PaymentGatewayApp.Mpgs.Checkout.initiate/2, and paste it below. Session ids
are single-use: a fresh one is needed per attempt.
session.id returned by INITIATE_CHECKOUT.data-cancel. Per the documentation this fires on a Payment Page
only — leaving it set on Embedded is how you confirm that for yourself.
Fill the fields above.
#embed-target