anchor.diff:        $machine->mustSucceed("echo hello");
         $machine->shutdown;
       '';
  +
   }
  
positive.code:           ../modules/testing/test-instrumentation.nix
            { key = "serial"; 
              boot.kernelParams = [ "console=tty1" "console=ttyS0" ];
              boot.loader.grub.timeout = pkgs.lib.mkOverride 0 {} 0; 
            }
          ];
      }).config.system.build.isoImage;
  
    testScript =
      ''
        createDisk("harddisk", 4 * 1024);
  
negative.code:           "mount LABEL=nixos /mnt",
        );
  
        # Create a NixOS configuration.
        $machine->mustSucceed(
            "mkdir -p /mnt/etc/nixos",
            "nixos-hardware-scan > /mnt/etc/nixos/hardware.nix",
        );
  
        my $cfg = $machine->mustSucceed("cat /mnt/etc/nixos/hardware.nix");
        print STDERR "Result of the hardware scan:$cfg\n";
  
        $machine->shutdown;
  
        # Now see if we can boot the installation.
  