Test Payment Requests are a great way to get a better understanding of how generating a Payment Request works. It's also great to see what your customers/clients will receive and the steps they follow to set up their payment.
A test request will not withdraw any money from the credit card/bank account you attach to it.
To make a Test Payment Request follow all the steps in generating a standard Payment Request (on how to do this go to this article), but in the final 'summary' (step 5) change 'Live Request' to 'Test' using the edit icon next to it then click confirm.
If you send a Test Request to a client they will not be able to make a payment using that request so it's important you do not send these to your clients.
Lastly you cannot change a Test Request to a Live Request after it has been sent.