anchor.diff:  
   %% Test single subscription and execution of event handler.
   event_stream_test(Config) ->
  -    [Worker1, Worker2] = ?config(op_worker_nodes, Config),
  +    [Worker1, Worker2 | _] = ?config(op_worker_nodes, Config),
       Self = self(),
       SessId1 = <<"session_id_1">>,
       SessId2 = <<"session_id_2">>,
  
positive.code: end_per_suite(Config) ->
      test_node_starter:clean_environment(Config).
  
  %%%===================================================================
  %%% Internal functions
  %%%===================================================================
  
  %%--------------------------------------------------------------------
  %% @private
  %% @doc
  %% Creates new test session.
  %% @end
  %%--------------------------------------------------------------------
  -spec session_setup(Worker :: node(), SessId :: session:id(),
      Cred :: session:credentials(), Con :: pid()) -> ok.
  session_setup(Worker, SessId, Cred, Con) ->
      test_utils:mock_new(Worker, communicator),
      test_utils:mock_expect(Worker, communicator, send, fun
          (_, _) -> ok
      end),
      ?assertEqual({ok, created}, rpc:call(Worker, session_manager,
          reuse_or_create_session, [SessId, Cred, Con])).
  
  
negative.code: %%--------------------------------------------------------------------
  -spec session_teardown(Worker :: node(), SessId :: session:id()) -> ok.
  session_teardown(Worker, SessId) ->
      ?assertEqual(ok, rpc:call(Worker, session_manager, remove_session, [SessId])).
  
  %%--------------------------------------------------------------------
  %% @private
  