I want to run some build tests without going through the process of leveling for 30 minutes a game by running a private server where I can control the variables. Does anyone know how I can create do this on my computer?
The closest you'll be able to get to this is to create a custom game in the client where your teammates and the other team are all bots (or it's just you by yourself). You can't host your own LoL server as all legitimate LoL servers are owned by Riot.
To create a custom game on the Riot servers:
If you play a custom, you can end it at any time without incurring a "leave" penalty.
After doing some digging and looking i have found the Github of someone called rolle3k. And it seems he has written an emulator for lol, now i don't know if this works... or if this is the new version. But it never hurts checking it out right?
Other then that, you could do what Shaun told you... but you are then stuck again with playing 30 min and such...