tests/dircolors: add xdg config test

tests/modules/programs/dircolors/default.nix

@@ -1 +1,4 @@
-{ dircolors-settings = ./settings.nix; }
+{
+  dircolors-settings = ./settings.nix;
+  dircolors-xdg-config-settings = ./xdg-config-settings.nix;
+}

tests/modules/programs/dircolors/xdg-config-settings.nix

@@ -0,0 +1,31 @@
+{ config, pkgs, ... }: {
+  config = {
+    home.preferXdgDirectories = true;
+
+    programs.zsh.enable = true;
+
+    programs.dircolors = {
+      enable = true;
+
+      settings = {
+        OTHER_WRITABLE = "30;46";
+        ".sh" = "01;32";
+        ".csh" = "01;32";
+      };
+
+      extraConfig = ''
+        # Extra dircolors configuration.
+      '';
+    };
+
+    nmt.script = ''
+      assertFileContent \
+        home-files/.config/dir_colors \
+        ${./settings-expected.conf}
+
+      assertFileRegex  \
+        home-files/.zshrc \
+        "eval \$(${pkgs.coreutils}/bin/dircolors -b ${config.xdg.configHome}/dir_colors)"
+    '';
+  };
+}