herbstluftwm: Fix error when no tags set

The default value for `xsession.windowManager.herbstluftwm.tags` is an
empty list, but the config file uses `builtins.head` on it, which causes
an error upon evaluation. With this change the tags configuration is
skipped if the list is empty.

modules/services/window-managers/herbstluftwm.nix

@@ -145,7 +145,8 @@ in {
 
         ${renderSettings cfg.settings}
 
-        if ${cfg.package}/bin/herbstclient object_tree tags.by-name | ${pkgs.gnugrep}/bin/grep default; then
+        ${lib.optionalString (cfg.tags != [ ]) ''
+          if ${cfg.package}/bin/herbstclient object_tree tags.default &>/dev/null; then
             herbstclient rename default ${
               lib.escapeShellArg (builtins.head cfg.tags)
             }
@@ -154,6 +155,7 @@ in {
           for tag in ${lib.escapeShellArgs cfg.tags}; do
             herbstclient add "$tag"
           done
+        ''}
 
         ${renderKeybinds cfg.keybinds}
 

tests/modules/services/window-managers/herbstluftwm/default.nix

@@ -1 +1,4 @@
-{ herbstluftwm-simple-config = ./herbstluftwm-simple-config.nix; }
+{
+  herbstluftwm-simple-config = ./herbstluftwm-simple-config.nix;
+  herbstluftwm-no-tags = ./herbstluftwm-no-tags.nix;
+}

tests/modules/services/window-managers/herbstluftwm/herbstluftwm-no-tags-autostart

@@ -0,0 +1,31 @@
+#!/nix/store/00000000000000000000000000000000-bash/bin/bash
+shopt -s expand_aliases
+
+# shellcheck disable=SC2142
+alias herbstclient='set -- "$@" ";"'
+set --
+
+herbstclient emit_hook reload
+
+# Reset everything.
+herbstclient attr theme.tiling.reset 1
+herbstclient attr theme.floating.reset 1
+herbstclient keyunbind --all
+herbstclient unrule --all
+
+
+
+
+
+
+
+
+
+
+
+
+
+herbstclient unlock
+
+@herbstluftwm@/bin/herbstclient chain ";" "$@"
+

tests/modules/services/window-managers/herbstluftwm/herbstluftwm-no-tags.nix

@@ -0,0 +1,16 @@
+{ lib, pkgs, ... }:
+
+{
+  xsession.windowManager.herbstluftwm = { enable = true; };
+
+  test.stubs.herbstluftwm = { };
+
+  nmt.script = ''
+    autostart=home-files/.config/herbstluftwm/autostart
+    assertFileExists "$autostart"
+    assertFileIsExecutable "$autostart"
+
+    normalizedAutostart=$(normalizeStorePaths "$autostart")
+    assertFileContent "$normalizedAutostart" ${./herbstluftwm-no-tags-autostart}
+  '';
+}

tests/modules/services/window-managers/herbstluftwm/herbstluftwm-simple-config-autostart

@@ -19,7 +19,7 @@ herbstclient set frame_bg_active_color '#000000'
 herbstclient set frame_gap '12'
 herbstclient set frame_padding '-12'
 
-if @herbstluftwm@/bin/herbstclient object_tree tags.by-name | /nix/store/00000000000000000000000000000000-gnugrep/bin/grep default; then
+if @herbstluftwm@/bin/herbstclient object_tree tags.default &>/dev/null; then
   herbstclient rename default '1'
 fi
 
@@ -27,6 +27,7 @@ for tag in '1' 'with space' 'wə1rd#ch@rs'\'''; do
   herbstclient add "$tag"
 done
 
+
 herbstclient keybind Mod4-1 use 1
 herbstclient keybind Mod4-2 use 2
 herbstclient keybind Mod4-Alt-Tab cycle -1

tests/modules/services/window-managers/herbstluftwm/herbstluftwm-simple-config.nix

@@ -39,6 +39,8 @@
     assertFileIsExecutable "$autostart"
 
     normalizedAutostart=$(normalizeStorePaths "$autostart")
-    assertFileContent "$normalizedAutostart" ${./autostart}
+    assertFileContent "$normalizedAutostart" ${
+      ./herbstluftwm-simple-config-autostart
+    }
   '';
 }