modules/files: fix creating configs of vim type

modules/top-level/files/submodule.nix

@@ -2,6 +2,7 @@
   name,
   config,
   lib,
+  pkgs,
   helpers,
   ...
 }:
@@ -22,6 +23,10 @@
       path = lib.mkDefault name;
       type = lib.mkDefault (if lib.hasSuffix ".vim" name then "vim" else "lua");
       # No need to use mkDerivedConfig; this option is readOnly.
-      plugin = helpers.writeLua derivationName config.content;
+      plugin =
+        let
+          writeContent = if config.type == "lua" then helpers.writeLua else pkgs.writeText;
+        in
+        writeContent derivationName config.content;
     };
 }

tests/test-sources/modules/files.nix

@@ -0,0 +1,29 @@
+{
+  after = {
+    files."after/ftplugin/python.lua" = {
+      localOpts.conceallevel = 1;
+
+      keymaps = [
+        {
+          mode = "n";
+          key = "<C-g>";
+          action = ":!python script.py<CR>";
+          options.silent = true;
+        }
+      ];
+    };
+  };
+
+  vim-type = {
+    files."plugin/default_indent.vim".opts = {
+      shiftwidth = 2;
+      expandtab = true;
+    };
+
+    extraConfigLuaPost = ''
+      vim.cmd.runtime("plugin/default_indent.vim")
+      assert(vim.o.shiftwidth == 2, "shiftwidth is not set")
+      assert(vim.o.expandtab, "expandtab is not set")
+    '';
+  };
+}