Does an app have to be published for IAP to work?

I have been testing my app in Internal Testing on the Google Play Developer Console and I have not published it yet, I set up my merchant account and assigned licensed testers. However, when I try to purchase somet$$anonymous$$ng on the test build of the app, it says "The item you requested is not available for purchase". Keep in mind that t$$anonymous$$s is my first time using IAP so I really don't know what I'm doing.