Personally, if they don't have a license, then no test ride. Tell them "I'll ride it around the block and show you it runs".
If they have the money and want to haul it off, take payment and give them the bike/title. They can do whatever they want after that, as long as they loaded and left your property and you have payment.
I really discourage test rides. If they want to argue, I say 'go to a dealership and see if they will let you test ride. I had to buy the bike without a test ride from them.' Most riders know this already. If they don't, they shouldn't be asking for a test ride to begin with... Unless you get off to watching them drop your bike at the end of the driveway before they paid for it.
I'm sure others have varying opinions, thats just the way I do it. Discourage test rides. But do start the bike, ride the bike in front of them, and show them al the ins and outs of starting etc...