zsh: respect xdg.enable for dotDir

Make sure we actually respect a user's `xdg.enable` preference.

Signed-off-by: Austin Horstman <khaneliman12@gmail.com>

tests/default.nix

@@ -130,6 +130,13 @@ let
             stateVersion = lib.mkDefault "18.09";
           };
 
+          # NOTE: Added 2025-12-27
+          # Avoid option change deprecation warning
+          # Remove after deprecation period
+          programs.zsh.dotDir = lib.mkIf (config.home.stateVersion == "18.09") (
+            lib.mkDefault "/home/hm-user"
+          );
+
           # Avoid including documentation since this will cause
           # unnecessary rebuilds of the tests.
           manual.manpages.enable = lib.mkDefault false;

tests/modules/programs/zsh/dotdir.nix

@@ -99,7 +99,7 @@ in
           "assertFileExists 'home-files/${if relDotDir == "" then "" else "${relDotDir}/"}.zshenv'"
 
           # for non-default dotDir only:
-          (lib.optionalString (case != "default" && case != "root-slash" && case != "root-no-slash") ''
+          (lib.optionalString (absDotDir != home) ''
             # check .zshenv in homeDirectory sources .zshenv in dotDir
             assertFileRegex home-files/.zshenv "source ${lib.escapeShellArg "${absDotDir}/.zshenv"}"