default-specialisation: add test for default specialisation

modules/misc/specialisation.nix

@@ -11,23 +11,21 @@ in {
     type = types.attrsOf (types.submodule {
       options = {
         configuration = mkOption {
-          type =
-            let
-              extended = extendModules {
-                modules = [{
-                  # Prevent infinite recursion
-                  specialisation = mkOverride 0 { };
+          type = let
+            extended = extendModules {
+              modules = [{
+                # Prevent infinite recursion
+                specialisation = mkOverride 0 { };
 
-                  # If used inside the NixOS/nix-darwin module, we get conflicting definitions
-                  # of `name` inside the specialisation: one is the user name coming from the
-                  # NixOS module definition and the other is `configuration`, the name of this
-                  # option. Thus we need to explicitly wire the former into the module arguments.
-                  # See discussion at https://github.com/nix-community/home-manager/issues/3716
-                  _module.args.name = mkForce name;
-                }];
-              };
-            in
-            extended.type;
+                # If used inside the NixOS/nix-darwin module, we get conflicting definitions
+                # of `name` inside the specialisation: one is the user name coming from the
+                # NixOS module definition and the other is `configuration`, the name of this
+                # option. Thus we need to explicitly wire the former into the module arguments.
+                # See discussion at https://github.com/nix-community/home-manager/issues/3716
+                _module.args.name = mkForce name;
+              }];
+            };
+          in extended.type;
           default = { };
           visible = "shallow";
           description = ''
@@ -89,25 +87,21 @@ in {
       message = "There can only be one default specialisation";
     }];
 
-    home.extraBuilderCommands =
-      let
-        link = n: v:
-          let pkg = v.configuration.home.activationPackage;
-          in "ln -s ${pkg} $out/specialisation/${n}";
-      in
-      ''
-        mkdir $out/specialisation
-        ${concatStringsSep "\n" (mapAttrsToList link cfg)}
-      '';
+    home.extraBuilderCommands = let
+      link = n: v:
+        let pkg = v.configuration.home.activationPackage;
+        in "ln -s ${pkg} $out/specialisation/${n}";
+    in ''
+      mkdir $out/specialisation
+      ${concatStringsSep "\n" (mapAttrsToList link cfg)}
+    '';
 
-    home.activation =
-      let
-        defaultSpecialisation = findFirst (s: s.default) null (attrValues cfg);
-      in
-      mkIf (defaultSpecialisation != null) (mkForce {
-        activateSpecialisation = ''
-          ${defaultSpecialisation.configuration.home.activationPackage}/activate
-        '';
-      });
+    home.activation = let
+      defaultSpecialisation = findFirst (s: s.default) null (attrValues cfg);
+    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;
+}