nixpkgs/nixos/tests/nats.nix

let

  port = 4222;
  username = "client";
  password = "password";
  topic = "foo.bar";

in import ./make-test-python.nix ({ pkgs, lib, ... }: {
  name = "nats";
  meta = with pkgs.lib; { maintainers = with maintainers; [ c0deaddict ]; };

  nodes = let
    client = { pkgs, ... }: {
      environment.systemPackages = with pkgs; [ natscli ];
    };
  in {
    server = { pkgs, ... }: {
      networking.firewall.allowedTCPPorts = [ port ];
      services.nats = {
        inherit port;
        enable = true;
        settings = {
          authorization = {
            users = [{
              user = username;
              inherit password;
            }];
          };
        };
      };
    };

    client1 = client;
    client2 = client;
  };

  testScript = let file = "/tmp/msg";
  in ''
    def nats_cmd(*args):
        return (
            "nats "
            "--server=nats://server:${toString port} "
            "--user=${username} "
            "--password=${password} "
            "{}"
        ).format(" ".join(args))

    def parallel(*fns):
        from threading import Thread
        threads = [ Thread(target=fn) for fn in fns ]
        for t in threads: t.start()
        for t in threads: t.join()

    start_all()
    server.wait_for_unit("nats.service")

    with subtest("pub sub"):
        parallel(
            lambda: client1.succeed(nats_cmd("sub", "--count", "1", "${topic}")),
            lambda: client2.succeed("sleep 2 && {}".format(nats_cmd("pub", "${topic}", "hello"))),
        )
  '';
})