anchor.diff:       begin
          %% Produce some messages into the topic:
          {_, L} = produce_payloads(Topic, Partition, Config),
  -       {ok, SubscriberPid} = start_subscriber(Config, [Topic], InitArgs),
  +       {ok, SubscriberPid} = start_subscriber(?group_id, Config, [Topic], InitArgs),
          %% And ack/commit them asynchronously:
          [begin
             {ok, #{offset := Offset}} = ?wait_message(Topic, Partition, I, _),
  
positive.code:      #{ timeout => 5000 },
       %% Run stage:
       begin
         {ok, SubscriberPid} = start_subscriber(Config, [Topic], InitArgs),
         %% send some messages
         [_, _, O3, _, O5] = [SendFun(I) || I <- lists:seq(1, 5)],
         %% Wait until the last one is processed
  
negative.code:        %% Send messages:
         {LastOffset, L} = produce_payloads(Topic, 0, Config),
         %% Start two subscribers competing for the partition:
         {ok, SubscriberPid1} = start_subscriber(?group_id, Config, [Topic], InitArgs),
         {ok, SubscriberPid2} = start_subscriber(?group_id, Config, [Topic], InitArgs),
         ?wait_message(_, _, _, LastOffset),
         L
       end,
  