test process-comose postgres + check functionality

lib.nix

@@ -8,8 +8,20 @@ in
       config,
       name,
       enableTui ? false,
+      modules ? [ ],
     }:
     let
+      merged_config = lib.foldl' (acc: elem: acc // elem.config) config modules;
+      checks = lib.concatStringsSep "\n" (
+        lib.concatMap (
+          attrs:
+          lib.mapAttrsToList (k: v: ''
+            echo "Running ${k}"
+            ${v}
+            echo "Passed ${k}"
+          '') attrs.checks
+        ) modules
+      );
       removeNullAndEmptyAttrs =
         attrs:
         let
@@ -29,7 +41,7 @@ in
         };
       configFile = toPCJson name (
         removeNullAndEmptyAttrs (
-          config
+          merged_config
           // {
             is_tui_disabled = !enableTui;
           }
@@ -39,16 +51,64 @@ in
     pkgs.writeShellApplication {
       inherit name;
       text = ''
-        PC_CONFIG_FILES=${configFile} ${pkgs.process-compose}/bin/process-compose "$@"
+        ${checks}
+         PC_CONFIG_FILES=${configFile} ${pkgs.process-compose}/bin/process-compose "$@"
 
       '';
     };
   mkPostgres =
     {
-      default_config ? false,
+      name,
+      default_config ? true,
+      config ? { },
+      extra_config ? '''',
+      package ? pkgs.postgresql,
       ...
     }:
     let
+      merged_config =
+        (
+          if default_config then
+            {
+              listen_addresses = "localhost";
+              port = 5432;
+              shared_buffers = "128MB";
+              worker_mem = "4M";
+              logging_collector = "off";
+
+            }
+          else
+            { }
+        )
+        // config;
+      toStr =
+        value:
+        if true == value then
+          "yes"
+        else if false == value then
+          "no"
+        else if lib.isString value then
+          "'${lib.replaceStrings [ "'" ] [ "''" value ]}'"
+        else
+          builtins.toString value;
+      configFile = pkgs.writeTextDir "postgresql.conf" (
+        lib.concatStringSep "\n" (
+          lib.mapAttrsToList (n: v: "${n} = ${toStr v}") (lib.filterAttrs (
+            lib.const (x: x != null)
+          )) merged_config
+        )
+      );
+      configFileCheck = pkgs.writeShellScript {
+        name = "postgresql-config-check-${name}";
+        text = ''
+          ${package}/bin/postgres -D${configFile} -C config_file
+          touch $out
+        '';
+      };
     in
-    { };
+    {
+      config.processes."${name}" = {
+      };
+      checks."postgresql${name}" = configFileCheck;
+    };
 }