anchor.diff:              case proplists:get_value(perf_configs, ConfExt, []) of
                   [] ->
                       Ext = proplists:get_value(perf_config, ConfExt, []),
  -                    exec_perf_config(M, F, Inputs, Ext, Repeats);
  +                    Ans = exec_perf_config(M, F, Inputs, Ext, Repeats),
  +                    ?assertEqual(ok, Ans);
                   Exts ->
  -                    lists:foreach(
  -                        fun(Ext) ->
  -                            exec_perf_config(M, F, Inputs, Ext, Repeats) end,
  -                        Exts)
  +                    AnsSum = lists:foldl(
  +                        fun(Ext, Acc) ->
  +                            Ans = exec_perf_config(M, F, Inputs, Ext, Repeats),
  +                            case Acc of
  +                                ok -> Ans;
  +                                _ -> Acc
  +                            end
  +                        end, ok, Exts),
  +                    ?assertEqual(ok, AnsSum)
               end;
           _ ->
               Ext = proplists:get_value(ct_config, ConfExt, []),
  
positive.code: %% @end
  %%--------------------------------------------------------------------
  -spec exec_perf_config(M :: atom(), F :: atom(), Inputs :: list(), Ext :: list(),
      ConfigName :: term(), Repeats :: integer()) -> ok.
  exec_perf_config(M, F, Inputs, Ext, ConfigName, Repeats) ->
      [I1] = Inputs,  % get first arg (test config)
      {ValuesSums, ValuesLists, OkNum, Errors} = exec_multiple_tests(M, F, [I1 ++ Ext], Repeats),
  
negative.code: 
      file:write(File, [iolist_to_binary(mochijson2:encode(prepare_to_write(Json3)))]),
      file:close(File),
      case Errors of
          [] -> ok;
          _ -> error
      end.
  
  %%--------------------------------------------------------------------
  %% @doc
  