anchor.diff:  
       ?assertEqual(ok, lfm_proxy:unlink(Worker1, <<"0">>, {guid, FileGuid})),
       ?assertEqual(ok, receive_file_removed_event()),
  +
       ?assertEqual(ok, ssl:send(Sock,
           fuse_test_utils:generate_subscription_cancellation_message(0, get_seq(Config, <<"user1">>), -Seq1))),
  +    ?assertMatch({ok, []},
  +        rpc:call(Worker1, subscription_manager, get_subscribers, [SubscriptionRoutingKey, undefined]), 10),
       ?assertEqual(ok, ssl:close(Sock)),
       ok.
   
  
positive.code: 
      rpc:call(Worker1, file_meta, make_space_exist, [<<"space_id", SpaceNum/binary>>]),
      ?assertEqual(ExpectedAns, receive_file_attr_changed_event()),
      ?assertEqual(ok, ssl:send(Sock,
          fuse_test_utils:generate_subscription_cancellation_message(0, get_seq(Config, User), -Seq1))),
      ?assertEqual(ok, ssl:close(Sock)),
      ok.
  
  
negative.code:     % Cleanup subscription
      ?assertEqual(ok, ssl:send(Sock,
          fuse_test_utils:generate_subscription_cancellation_message(0, get_seq(Config, User), -Seq2))),
      ?assertMatch([{ok, []}, {ok, []}],
          rpc:call(Worker1, subscription_manager, get_attr_event_subscribers, [FileGuid, undefined, true]), 10),
      ?assertEqual(ok, ssl:close(Sock)),
      ok.
  
  