tests: add buildwmwithbootloader stub

tests/buildvmwithbootloader/build-vm.nix

@@ -0,0 +1,32 @@
+{ system ? builtins.currentSystem
+, vmPkgsPath
+, buildPkgsPath
+, nixosConfigPath
+}:
+
+let
+  buildPkgs = import buildPkgsPath {};
+  vmPkgs'= import vmPkgsPath {};
+  vmPkgs = vmPkgs' // {
+    runtimeShell = "${vmPkgs'.bash}/${vmPkgs'.bash.shellPath}";
+  };
+
+  importWithPkgs = { path, pkgs }: args: import path (args // { inherit pkgs; });
+ 
+  nixosConfig = importWithPkgs { path = "${nixosConfigPath}"; pkgs = vmPkgs; };
+  vmConfig = importWithPkgs { path = "${buildPkgsPath}/nixos/modules/virtualisation/qemu-vm.nix"; pkgs = vmPkgs; };
+  evalConfig = importWithPkgs { path = "${vmPkgsPath}/nixos/lib/eval-config.nix"; pkgs = null; };
+
+  vmWithBootLoaderConfigMixed = (evalConfig {
+    modules = [
+      nixosConfig
+      vmConfig
+      {
+        virtualisation.useBootLoader = true; 
+      }
+
+    ];
+  }).config;
+in {
+  vmWithBootLoaderMixed = vmWithBootLoaderConfigMixed.system.build.vm;
+}