anchor.diff:    # a test script fragment `createPartitions', which must create
     # partitions and filesystems, and a configuration.nix fragment
     # `fileSystems'.
  -  testScriptFun = { createPartitions, fileSystems, testChannel }:
  +  testScriptFun = { createPartitions, fileSystems, testChannel, grubVersion }:
       ''
         createDisk("harddisk", 4 * 1024);
   
  
positive.code:     '';
  
  
    makeTest = { createPartitions, fileSystems, testChannel ? false }:
      { inherit iso;
        nodes = if testChannel then { inherit webserver; } else { };
        testScript = testScriptFun {
          inherit createPartitions fileSystems testChannel;
        };
      };
  
  
negative.code:             "''${modulesPath}/testing/test-instrumentation.nix"
            ];
  
          boot.loader.grub.version = ${toString grubVersion};
          ${optionalString (grubVersion == 1) ''
            boot.loader.grub.splashImage = null;
          ''}
          boot.loader.grub.device = "/dev/vda";
          boot.loader.grub.extraConfig = "serial; terminal_output.serial";
          boot.initrd.kernelModules = [ "ext3" "virtio_console" ];
  