anchor.diff:  
       _Config.
   
  +init_per_group(with_sync_join, Config) ->
  +    [{parallelism, 1}, {sync_join, true}] ++ Config;
   init_per_group(with_monotonic_channels, Config) ->
       [{parallelism, 1}, {channels, [{monotonic, vnode}, gossip]}] ++ Config;
   init_per_group(with_channels, Config) ->
  
positive.code: 
       {group, with_channels, [parallel]},
       
       {group, with_monotonic_channels, [parallel]}
      ].
  
  groups() ->
  
negative.code:       [default_manager_test]},
  
       {with_monotonic_channels, [],
        [default_manager_test]},
  
       {with_sync_join, [],
        [default_manager_test]}
      ].
  
  