anchor.diff:  
         {
           services.redis.enable = true;
  -        services.redis.unixSocket = "/run/redis/redis.sock";
  +        services.redis.unixSocket = redisSocket;
  +
  +        # Allow access to the unix socket for the "redis" group.
  +        services.redis.settings.unixsocketperm = "770";
  +
  +        users.users."member" = {
  +          createHome = false;
  +          description = "A member of the redis group";
  +          extraGroups = [
  +            "redis"
  +          ];
  +          group = "users";
  +          shell = "/bin/sh";
  +        };
         };
     };
   
  
positive.code:     start_all()
      machine.wait_for_unit("redis")
      machine.wait_for_open_port("6379")
      machine.succeed("redis-cli ping | grep PONG")
      machine.succeed("redis-cli -s /run/redis/redis.sock ping | grep PONG")
    '';
  })
  
negative.code: import ./make-test-python.nix ({ pkgs, ... }:
  let
    redisSocket = "/run/redis/redis.sock";
  in
  {
    name = "redis";
    meta = with pkgs.stdenv.lib.maintainers; {
      maintainers = [ flokli ];
  