Best way to test/fake IAP calls and results without committing to an IAP platform?

[Midknight]

I'm trying to get the hang of the IAP systems and I want to simulate the result of the purchase of an item in my catalog but I'm not at a point of committing to any platform. My project is in develop on windows using Unity; How can I trigger a purchase without have to setup one of these IAP platforms? I noticed there is check box in Advanced Settings called "Fake Windows Store In-app Purchase Success" but I don't see any documentation... Is it somehow possible to fake the windows store without having to configure anything on the platform? Can someone suggest how I can simulate the effect of a platform IAP without having to sign up and configuring? Otherwise, what platform developing w/ unity on windows is going to be the path of least resistance to setup; I looked into Steam but it is slightly more of commitment that I'm ready to take.