anchor.diff:                              , parameters = Parameters
                               , events = Events
                               , pid = Pid },
  -            Devices = orddict:store( Device#device.id, Device, State#state.devices ),
  +            Devices = orddict:store( DeviceId, Device, State#state.devices ),
               NewState = State#state{ devices = Devices },
               { reply, { ok, Device#device.id }, NewState };
           { error, _ } = Error ->
  
positive.code: list_devices( Server ) ->
      gen_server:call( Server, list_devices ).
  
  -spec poll_device_event( pid() , device_id(), binary() ) ->
      { ok, term() } | { error, no_such_device } | { error | no_such_event }.
  poll_device_event( Server, Id, Event ) ->
      gen_server:call( Server, { poll_device_event, Id, Event } ).
  
  %% ===================================================================
  %% gen_server callbacks
  
negative.code:                  fun( _Driver, _Parameters ) -> { error, enoent } end ),
      StartResult = start_device( Pid, dummy_driver_config( ) ),
      [ { "error propagated", ?_assertMatch( { error, _Error }, StartResult ) } ].
  
  
  test_add_list_devices( Pid ) ->
  