add configuration for VM test

testing.nix

@@ -0,0 +1,27 @@
+{ lib, ... }:
+
+let
+  secrets = toString ./secrets;
+in
+
+{
+  imports = [
+    <nixpkgs/nixos/modules/virtualisation/qemu-vm.nix>
+    ./configuration.nix
+  ];
+
+  # Ensure secrets are accessible by the
+  # activation scripts at runtime.
+  virtualisation.qemu.options = [
+    "-virtfs local,path=${secrets},security_model=none,mount_tag=secrets"
+  ];
+  fileSystems = lib.mkVMOverride {
+   "${secrets}" =
+      { device = "secrets";
+        fsType = "9p";
+        options = [ "trans=virtio" "version=9p2000.L" ];
+        neededForBoot = true;
+      };
+  };
+
+}