nixos: add test for postgresql, fixes #11146

nixos/release.nix

···
   tests.openssh = callTest tests/openssh.nix {};
   tests.panamax = hydraJob (import tests/panamax.nix { system = "x86_64-linux"; });
   tests.peerflix = callTest tests/peerflix.nix {};
+  tests.postgresql = callTest tests/postgresql.nix {};
   tests.printing = callTest tests/printing.nix {};
   tests.proxy = callTest tests/proxy.nix {};
   tests.pumpio = callTest tests/pump.io.nix {};

nixos/tests/postgresql.nix

···
+import ./make-test.nix ({ pkgs, ...} : {
+  name = "postgresql";
+  meta = with pkgs.stdenv.lib.maintainers; {
+    maintainers = [ zagy ];
+  };
+
+  nodes = {
+    master =
+      { pkgs, config, ... }:
+
+      {
+        services.postgresql.enable = true;
+        services.postgresql.initialScript =  pkgs.writeText "postgresql-init.sql"
+          ''
+          CREATE ROLE postgres WITH superuser login createdb;
+          '';
+      };
+  };
+
+  testScript = ''
+    startAll;
+    $master->waitForUnit("postgresql");
+    $master->sleep(10); # Hopefully this is long enough!!
+    $master->succeed("echo 'select 1' | sudo -u postgres psql");
+  '';
+})