Anytime you need to talk to a third party API, you need to test in prod.
Some people have sandbox apis. They are generally broken and not worth it. See eBay for super in depth sandbox API that never works.
You can read the docs 100 times over. At the end of the day, the API is going to work like it works. So you kind of “have to” test in prod for these guys.
Ditto regarding Paypal: you need a sandbox API token to get started with it. Their sandbox token generator was broken for MONTHS, I could not believe it. By the time we got the token, we already fixed all bugs on our side the hard way - by testing in prod - and moved on.
There was a sandbox but it never behaved like the prod environments. To the point I had to have a flag to tell my order entry code if we were being certified in the sandbox or actually trading in prod.
I’ve heard that got better after they replaced the gateways with fpga but don’t know for sure.
Some people have sandbox apis. They are generally broken and not worth it. See eBay for super in depth sandbox API that never works.
You can read the docs 100 times over. At the end of the day, the API is going to work like it works. So you kind of “have to” test in prod for these guys.