Does PayPal always return a payer_id?

Question

I understand that when the customer logs into PayPal and uses their PayPal account, PayPal will send us the customer's payer_id. But what happens if the customer does not log into PayPal and just uses a credit card to process the payment? And is there any way to fake that in the Sandbox? Does PayPal supply test credit card numbers? One for Success, and others for various types of failure?

(This is PayPal Website Payments Standard).

Answer 1

The answer I received from the PayPal developer forums was:

A payer_id is returned whether the buyer pays with a PayPal account or uses their credit card without logging into an account.

You can generate test card number in the sandbox by following the steps below:

First login to your buyer sandbox account and generate a test credit card by following the steps below:

Click on Profile

Click on Credit card

Click on Add

Select the card type (currently, the sandbox will generate test visa card numbers)

Copy the card here and click on cancel

** Don't add the card to your account**

Now use this test card number, any expiration date in the future, 000 for the CVV2 number, any address in a valid format and any name to test again.

These test cards will result in a success. For website payments standard, to simulate failure with a test card number, you can enter any random 16 digits for the card number. However, with website payments standard, if a transaction fails, no response is sent to the merchant.

Thanks.