My map is at 0% popularity, when I host a game with my map nobody joins, ever, and I don't expect they ever will.
Is there no way to get new custom maps played other than to advertise the games to friends/internet?

I want to test the map a bit before I post it up on forums and map making communities. I only have 3 friends on bnet, what do I do.

You have this all wrong.
Map-Making Communities are there to help you test and produce the maps. Share the map into the SC2 Map Production forum, call a Test Night (date + hour please), and people will show up. From there, your games/hour increases just as your map's quality increases as well.

allrighty.
i will try that. doubt it will be enough to get my map to the level of popularity where players will join it on bnet, but its worth a shot eh?..

This may be of some use to you:
Useful Link