What's the right way to make sure you've implemented a payment service integration correctly? Do payment processors provide services (or checklists to go down)

What's the right way to make sure you've implemented a payment service integration correctly? Do payment processors provide services (or checklists to go down) to make sure you haven't made any of the common mistakes? Or is the answer a professional pentest? In an ideal world I feel like you'd want two layers of defense in case one team miss something...