anchor.diff:  
   prerequisites() ->
       [
  -     { "docker in $PATH?",
  -       fun (_Config) ->
  -               {done, 0, <<"Docker", _/bytes>>} = erlsh:oneliner("docker -v")
  -       end}
  +     { "docker in $PATH", fun (_Config) -> {_, _, <<"Docker", _/bytes>>} = sh("docker -v") end },
  +     { "git in $PATH", fun (_) -> {_, _, <<"usage: git", _/bytes>>} = sh("git --help") end }
       ].
   
   end_per_suite(_Config) ->
  
positive.code:     end.
  
  container_name(Prefix) ->
      ?b2l(?il2b([Prefix, base64:encode(crypto:strong_rand_bytes(9))])).
  
  which(Command) ->
      {done, 0, BPath} = sh("which " ++ Command),
  
negative.code:     start_container(Name, Args),
      try
          sh(["docker exec ", Name, " echo a"]),
          ct:pal("git commit: ~p", [current_git_commit()]),
          ct:fail("not implemented yet")
      after
          sh("docker stop " ++ Name)
  