anchor.diff:    # a test script fragment `createPartitions', which must create
     # partitions and filesystems.
     testScriptFun = { bootLoader, createPartitions, grubVersion, grubDevice, grubUseEfi
  -                  , grubIdentifier, preBootCommands, extraConfig
  +                  , grubIdentifier, preBootCommands, postBootCommands, extraConfig
                     , testSpecialisationConfig
                     }:
       let iface = if grubVersion == 1 then "ide" else "virtio";
  
positive.code:       };
  
        testScript = testScriptFun {
          inherit bootLoader createPartitions preBootCommands
                  grubVersion grubDevice grubIdentifier grubUseEfi extraConfig
                  testSpecialisationConfig;
        };
  
negative.code:       with subtest("We should find a file named /etc/gitconfig"):
            machine.succeed("test -e /etc/gitconfig")
  
        ${postBootCommands}
        machine.shutdown()
      '';
  
  
    makeInstallerTest = name:
      { createPartitions, preBootCommands ? "", postBootCommands ? "", extraConfig ? ""
      , extraInstallerConfig ? {}
      , bootLoader ? "grub" # either "grub" or "systemd-boot"
      , grubVersion ? 2, grubDevice ? "/dev/vda", grubIdentifier ? "uuid", grubUseEfi ? false
  