anchor.diff:  % for unit tests
   -spec unittest_lease_update(lease_t(), lease_t(), active | passive) -> ok | failed.
   unittest_lease_update(Old, New, Mode) ->
  +    ?ASSERT(util:is_unittest()), % may only be used in unit-tests
       comm:send_local(pid_groups:get_my(dht_node),
                       {l_on_cseq, unittest_update, Old, New, Mode, self()}),
       trace_mpath:thread_yield(),
  
positive.code: 
  -spec unittest_clear_lease_list(Pid::comm:erl_local_pid()) -> ok.
  unittest_clear_lease_list(Pid) ->
      comm:send_local(Pid,
                      {l_on_cseq, unittest_clear_lease_list, comm:this()}),
      trace_mpath:thread_yield(),
  
negative.code: on({l_on_cseq, unittest_update,
      Old = #lease{id=Id, epoch=OldEpoch,version=OldVersion},
      New, Mode, Caller}, State) ->
      ?ASSERT(util:is_unittest()), % may only be used in unit-tests
      %% io:format("renew ~p~n", [Old]),
      ContentCheck = is_valid_update(OldEpoch, OldVersion),
      DB = get_db_for_id(Id),
  