You can make test payments immediately by setting up a Bogus Gateway even if you don't have Payments enabled in Shopify.

Even if you don't activate the standard payment method, Shopify Payments, you can make test payments right away by following the instructions here to set up a payment method called Bogus Gateway .

Test using Shopify's Bogus Gateway

Bogus Gateway is a payment gateway that any store can use to create test orders.

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Make a test payment using Bogus Gateway