Testing Payment Flows Without the Payment SDK

Payment integrations are one of the hardest things to test in a web app. The SDK renders its own UI, controls its own form fields, and fires callbacks when the user completes a payment. You can't programmatically fill in a credit card number. You can't simulate a declined card. And if the SDK fails to initialize — because of a network issue, a bad API key, or a test environment misconfiguration — your entire test falls apart. You can mock the SDK's setup endpoint to get the SDK rendering, the fo