As of about May 2014 this year, searching Google for "ios in app purchase promotion code", yields lots of news sites reporting the same thing - Apple seem to be working on allowing promotion codes for testing in-app purchases as evidenced by a screenshot from EA games.
My question is; does anybody know how to do this yet? I logged into the new iTunesConnect interface but can't find any link and nothing appears in the Apple docs from what I can find.
Ideally I'm looking to create a code for a monthly subscription but they may only be allowed for consumables. With the lack of actual info on IAP promo codes my guess is that the feature hasn't been officially made available yet and that EA games were invited by Apple to test it out.