auth_set_up_and_test.config.passport.snippet.js

User.findOne({ 'local.email' :  email }, function(err, user) {
    // if there are any errors, return the error
    if (err)
        return done(err);

    // check to see if theres already a user with that email
    if (user) {
        return done(null, { error: 'That email is already taken.' });
    } else {

        // create the user
        var newUser            = new User();

        newUser.local.email    = email;
        newUser.local.password = newUser.generateHash(password);

        newUser.save(function(err) {
            if (err)
                throw err;

            return done(null, newUser);
        });
    }

});