Is it possible to have a bot-only custom game?

I have been wondering lately that can I create a custom game where 5 bots will play out the game, and I'm the spectator? I've always been interested into how bots play the games (even though they're dumb). So far all I can do is make a 4v4 bot game and I'm on one of the team just to watch the game without interfere the match. Any helps would be greatly appreciated :)). Thanks.