default-specialisation: add test for default specialisation

modules/misc/specialisation.nix

@@ -17,8 +17,7 @@ in
       lib.types.submodule {
         options = {
           configuration = lib.mkOption {
-            type =
-              let
+            type = let
               extended = extendModules {
                 modules = [
                   {
@@ -34,8 +33,7 @@ in
                   }
                 ];
               };
-              in
-              extended.type;
+            in extended.type;
             default = { };
             visible = "shallow";
             description = ''
@@ -105,25 +103,21 @@ in
         message = "<name> in specialisation.<name> cannot contain a forward slash.";
       }) (lib.attrNames config.specialisation);
 
-    home.extraBuilderCommands =
-      let
+    home.extraBuilderCommands = let
       link =
         n: v:
         let
           pkg = v.configuration.home.activationPackage;
         in
         "ln -s ${pkg} $out/specialisation/${lib.escapeShellArg n}";
-      in
-      ''
+    in ''
       mkdir $out/specialisation
       ${lib.concatStringsSep "\n" (lib.mapAttrsToList link cfg)}
     '';
 
-    home.activation =
-      let
+    home.activation = let
       defaultSpecialisation = findFirst (s: s.default) null (attrValues cfg);
-      in
-      mkIf (defaultSpecialisation != null) (mkForce {
+    in mkIf (defaultSpecialisation != null) (mkForce {
       activateSpecialisation = ''
         ${defaultSpecialisation.configuration.home.activationPackage}/activate
       '';

tests/modules/misc/specialisation/default-specialisation.nix

@@ -0,0 +1,10 @@
+{ config, ... }: {
+  home.file.testfile.text = "not special";
+  specialisation = { test.default = true; };
+
+  nmt.script = ''
+    assertFileExists activate
+    assertFileContains activate \
+      "${config.specialisation.test.configuration.home.activationPackage}/activate"
+  '';
+}

tests/modules/misc/specialisation/default.nix

@@ -1 +1,4 @@
-{ specialisation = ./specialisation.nix; }
+{
+  specialisation = ./specialisation.nix;
+  default-specialisation = ./default-specialisation.nix;
+}