tests: Add a test for the nixos module

flake-modules/tests.nix

@@ -6,6 +6,7 @@
   perSystem = {
     pkgs,
     config,
+    system,
     makeNixvimWithModuleUnfree,
     makeNixvimWithModule,
     ...
@@ -39,6 +40,17 @@
           nixvim = self;
         })
         .activationPackage;
+
+      nixos =
+        (import ../tests/modules/nixos.nix {
+          inherit system;
+          inherit (inputs) nixpkgs;
+          nixvim = self;
+        })
+        .config
+        .system
+        .build
+        .toplevel;
     };
   };
 }

tests/modules/nixos.nix

@@ -0,0 +1,21 @@
+{
+  nixvim,
+  nixpkgs,
+  system,
+}:
+nixpkgs.lib.nixosSystem {
+  inherit system;
+
+  modules = [
+    {
+      system.stateVersion = "23.11";
+      boot.loader.systemd-boot.enable = true;
+      fileSystems."/" = {device = "/non/existent/device";};
+
+      programs.nixvim = {
+        enable = true;
+      };
+    }
+    nixvim.nixosModules.nixvim
+  ];
+}