I mean, like, instead of lynching someone, the villagers would vote on whom to test. It would be the same, except that person doesn't die, and the villagers don't know if the person is then turned by the wolf that night unless they test the person again.
The wolves would win if they manage to turn enough to outnumber the peasants... the villagers would win if they test all the wolves (which will put them out of the game because if I were a peasant, I would kill the wolf!). I'm thinking that the Hunter would be a good role - they could use their power once and only once. Instead of being turned by the wolves, they remain a peasant, and they turn one of the wolves back to a peasant as well. The guardian would protect people from being turned by the wolves... Maybe the alchemist, too. I'm not sure yet.