kanshi: add support for output aliases

- Add `services.kanshi.profiles.<name>.outputs.*.alias` to support new
  alias directive from kanshi [1].
  - Add an assertion to reject aliases not on global scope, which are
    not allowed on kanshi [2].
  - Add a new test to check alias rejection, `alias-assertion`.
- Add relevant coverage by modifying the existing "new-configuration"
  test.
- Kanshi also doesn't allow wildcards on global scope [3], correct the
  faulty test case.

[1]: 1ed86ce523
[2]: 1605f7c813/item/doc/kanshi.5.scd (L78)
[3]: 1605f7c813/item/doc/kanshi.5.scd (L80)

modules/services/kanshi.nix

@@ -123,6 +123,15 @@ let
         '';
       };
 
+      alias = mkOption {
+        type = types.nullOr types.str;
+        default = null;
+        example = "laptopMonitor";
+        description = ''
+          Defines an alias for the output
+        '';
+      };
+
       adaptiveSync = mkOption {
         type = types.nullOr types.bool;
         default = null;
@@ -135,15 +144,16 @@ let
     };
   };
 
-  outputStr =
-    { criteria, status, mode, position, scale, transform, adaptiveSync, ... }:
+  outputStr = { criteria, status, mode, position, scale, transform, adaptiveSync
+    , alias, ... }:
     ''output "${criteria}"'' + optionalString (status != null) " ${status}"
     + optionalString (mode != null) " mode ${mode}"
     + optionalString (position != null) " position ${position}"
     + optionalString (scale != null) " scale ${toString scale}"
     + optionalString (transform != null) " transform ${transform}"
     + optionalString (adaptiveSync != null)
-    " adaptive_sync ${if adaptiveSync then "on" else "off"}";
+    " adaptive_sync ${if adaptiveSync then "on" else "off"}"
+    + optionalString (alias != null) " alias \$${alias}";
 
   profileModule = types.submodule {
     options = {
@@ -296,6 +306,14 @@ in {
           message =
             "Cannot mix kanshi.settings with kanshi.profiles or kanshi.extraConfig";
         }
+        {
+          assertion = let profiles = filter (x: x ? profile) cfg.settings;
+          in length
+          (filter (x: any (a: a ? alias && a.alias != null) x.profile.outputs)
+            profiles) == 0;
+          message =
+            "Output kanshi.*.output.alias can only be defined on global scope";
+        }
       ];
     }
 

tests/modules/services/kanshi/alias-assertion.nix

@@ -0,0 +1,18 @@
+{ config, pkgs, ... }: {
+  config = {
+    services.kanshi = {
+      enable = true;
+      package = config.lib.test.mkStubPackage { };
+      settings = [{
+        profile.name = "nomad";
+        profile.outputs = [{
+          criteria = "eDP-1";
+          alias = "test";
+        }];
+      }];
+    };
+
+    test.asserts.assertions.expected =
+      [ "Output kanshi.*.output.alias can only be defined on global scope" ];
+  };
+}

tests/modules/services/kanshi/default.nix

@@ -1,4 +1,5 @@
 {
   kanshi-basic-configuration = ./basic-configuration.nix;
   kanshi-new-configuration = ./new-configuration.nix;
+  kanshi-alias-assertion = ./alias-assertion.nix;
 }

tests/modules/services/kanshi/new-configuration.conf

@@ -1,12 +1,12 @@
 include "path/to/included/file"
-output "*" enable
+output "Iiyama North America PLE2483H-DP" alias $iiyama
 profile nomad {
   output "eDP-1" enable
 }
 
 profile desktop {
   output "eDP-1" disable
-  output "Iiyama North America PLE2483H-DP" enable position 0,0
+  output "$iiyama" enable position 0,0
   output "Iiyama North America PLE2483H-DP 1158765348486" enable mode 1920x1080 position 1920,0 scale 2.100000 transform flipped-270
   exec echo "1 two 3"
   exec echo "4 five 6"

tests/modules/services/kanshi/new-configuration.nix

@@ -7,8 +7,8 @@
         { include = "path/to/included/file"; }
         {
           output = {
-            criteria = "*";
-            status = "enable";
+            criteria = "Iiyama North America PLE2483H-DP";
+            alias = "iiyama";
           };
         }
         {
@@ -27,7 +27,7 @@
               status = "disable";
             }
             {
-              criteria = "Iiyama North America PLE2483H-DP";
+              criteria = "$iiyama";
               status = "enable";
               position = "0,0";
             }