Run one complete test order on mobile and desktop. Check discounts, tax, shipping, payment, confirmation email, fulfillment, cancellation, and refund.
Duplicate the live theme. Change one thing, use the same page and device, and record what happened. If the change breaks a customer path, roll it back before touching production.
Check the home, collection, product, cart, and checkout path on a phone. Confirm the page still works with a slow connection and that the business owner for the feature agrees it can change.
Run one complete test order on mobile and desktop. Check discounts, tax, shipping, payment, confirmation email, fulfillment, cancellation, and refund.
Source: Shopify theme performance guidance. Reviewed Sep 22, 2026.