Test PayPal payment Shopify: start from the cart

A PayPal button on the cart page can send the shopper to PayPal before the store has asked for a shipping address, a discount code or a tax region. PayPal works out some details itself, and the store has to match them when the shopper returns. If the cart total and the PayPal total differ, the shopper sees two numbers and no explanation. If the return lands on a page that does not show the order, the shopper assumes the purchase failed. The fault sits in the steps between the button and the return, and a test that starts at checkout never touches it.

• Start PayPal from the cart and from checkout, and compare the two totals in the PayPal window.
• Check that discount codes survive the trip to PayPal and back to the store.
• Confirm the address PayPal returns matches the one the shopper gave, or the one you expected.
• Note whether the return page shows the order number and a paid status.
• Check the shipping rate PayPal shows matches the rate the store charges.

A PayPal start from the cart and a start from checkout send different information. The cart start can happen before the shopper has entered an address, so PayPal may estimate shipping on its own, or leave it for the return. The checkout start happens after the store knows the address and the rate, so its numbers are more complete. Neither is wrong by itself. The problem is a shopper who sees both and cannot tell which total is the one they will pay.

Run both starts on the same cart and note every line in each PayPal window. Look at the item list, the quantity, the discount, the shipping and the total. Any line that is missing or different is a candidate for the fault, and the cart start is often the first place to look. Write each difference down with the window it came from. Repeat the comparison after each change to the cart or the shipping rules.

After PayPal, the shopper comes back to the store, and the store decides what to show. If the return page lacks the order number, the shopper may think nothing was bought and start again. If the cart still holds the items, the shopper may try to pay again. A return that lands on a clean confirmation page is the one a buyer trusts. Check which of those outcomes the return gives, using a test order rather than a screenshot of the button.

In the store admin, check that the order exists, shows as paid and lists the items and totals the shopper saw. A missing order after a successful PayPal payment is usually a notification fault, not a cart fault, and it needs a different fix. Write down which screen the shopper saw after the return, so a support message can say exactly what happened.

A simulated visitor starts PayPal from the cart, then from checkout, and records each window it opens. It stops on PayPal's page because a visitor has no PayPal account to finish with. The screenshot records whatever the window shows before the test stops, including any total it displays, but the test does not reach the return to your store. Finish the return with a sandbox buyer account or one small live order you refund, and read the return page yourself.

A new discount app, a shipping rule or a theme update can change what the cart sends to PayPal without any visible change on the cart page. Rerun both PayPal starts with the same cart after each of those changes, and compare the totals line by line. Check the return page with one test order each time, since a changed total is easy to miss in the cart.