add testing VM

internal_testsuites/flake.nix

@@ -0,0 +1,46 @@
+{
+  outputs = { self, nixpkgs, }: {
+    nixosModules.vm = { ... }: {
+      # Make VM output to the terminal instead of a separate window
+      virtualisation.vmVariant.virtualisation.graphics = false;
+    };
+
+    nixosModules.base = { pkgs, ... }: {
+      system.stateVersion = "23.11";
+
+      # Configure networking
+      networking.useDHCP = false;
+      networking.interfaces.eth0.useDHCP = true;
+
+      # Create user "test"
+      services.getty.autologinUser = "tester";
+      users.users.test.isNormalUser = true;
+
+      # Enable passwordless ‘sudo’ for the "test" user
+      users.users.test.extraGroups = [ "wheel" ];
+      security.sudo.wheelNeedsPassword = false;
+    };
+
+    nixosConfigurations.linuxVM = nixpkgs.lib.nixosSystem {
+      system = "x86_64-linux";
+      modules = [ self.nixosModules.base self.nixosModules.vm ];
+    };
+    packages.x86_64-linux.linuxVM =
+      self.nixosConfigurations.linuxVM.config.system.build.vm;
+
+    nixosConfigurations.darwinVM = nixpkgs.lib.nixosSystem {
+      system = "aarch64-linux";
+      modules = [
+        self.nixosModules.base
+        self.nixosModules.vm
+        {
+          virtualisation.vmVariant.virtualisation.host.pkgs =
+            nixpkgs.legacyPackages.aarch64-darwin;
+        }
+      ];
+    };
+    packages.aarch64-darwin.darwinVM =
+      self.nixosConfigurations.darwinVM.config.system.build.vm;
+
+  };
+}