Cart behavior checklist
- Correct product appears after add-to-cart.
- Correct variant title, SKU or option label appears in the cart.
- Quantity controls update line total and cart total.
- Removal clears the item and shows the expected empty-cart state.
- Price changes remain consistent between product page and cart.
- Discount codes produce the expected customer-facing result.
- Cart drawer and cart page both preserve the selected item.
- Checkout button or link points toward the checkout handoff.
Common failure patterns
Variant mismatch is the most visible cart failure: the shopper selects Blue / Medium, but the cart shows another option. Discount mismatch is another common issue when storefront code, automatic discounts and checkout behavior do not agree.
Useful example
For a cart drawer store, add one product variant, change quantity to two, close and reopen the drawer, then continue to the cart page. The selected variant and total should remain stable across both surfaces.