anchor.diff:  %%       N = integer() | forever
   %% @doc returns list of test case group definitions.
   groups() ->
  -    [].
  +  [].
   
   %% @spec all() -> Tests | {skip, Reason}
   %% where
  
positive.code: %%       Reason = term()
  %% @doc runs initialization before matching test group is executed.
  init_per_group(_GroupName, Config) ->
      Config.
  
  %% @spec end_per_group(GroupName, Config0) -> ok | {save_config, Config1}
  %% where
  
negative.code: %%       Reason = term()
  %% @doc runs cleanup for matching test case.
  end_per_testcase(_TestCase, _Config) ->
    ok.
  
  %% @spec groups() -> [Group]
  %% where
  