nixos/powerdns: add test

nixos/release.nix

···
   tests.postgresql = callSubTests tests/postgresql.nix {};
   tests.pgmanage = callTest tests/pgmanage.nix {};
   tests.postgis = callTest tests/postgis.nix {};
+  tests.powerdns = callTest tests/powerdns.nix {};
   #tests.pgjwt = callTest tests/pgjwt.nix {};
   tests.predictable-interface-names = callSubTests tests/predictable-interface-names.nix {};
   tests.printing = callTest tests/printing.nix {};

nixos/tests/powerdns.nix

···
+import ./make-test.nix ({ pkgs, ... }: {
+  name = "powerdns";
+
+  nodes.server = { config, pkgs, ... }: {
+    services.powerdns.enable = true;
+  };
+
+  testScript = ''
+    $server->waitForUnit("pdns");
+    $server->succeed("${pkgs.dnsutils}/bin/dig version.bind txt chaos \@127.0.0.1");
+  '';
+})