anchor.diff:  rec {
     examples = callPackage ./examples.nix {
       inherit buildImage buildLayeredImage fakeNss pullImage shadowSetup buildImageWithNixDb;
  +  };
  +
  +  tests = {
  +    inherit (nixosTests)
  +      docker-tools
  +      docker-tools-overlay
  +      # requires remote builder
  +      # docker-tools-cross
  +      ;
     };
   
     pullImage =
  
positive.code: 
    # We need to sum layer.tar, not a directory, hence tarsum instead of nix-hash.
    # And we cannot untar it, because then we cannot preserve permissions etc.
    tarsum = pkgs.tarsum;
  
    # buildEnv creates symlinks to dirs, which is hard to edit inside the overlay VM
    mergeDrvs =
  
negative.code: , storeDir ? builtins.storeDir
  , substituteAll
  , symlinkJoin
  , tarsum
  , util-linux
  , vmTools
  , writeReferencesToFile
  