adds tests for models.NotificationEvent.getNewMentionedUsers method.
adds tests for models.NotificationEvent.getNewMentionedUsers method.

yona-projects/yona,doortts/fork-yobi,brainagenet/yobi,Limseunghwan/oss,bloodybear/yona,brainagenet/yobi,ihoneymon/yobi,ahb0327/yobi,yona-projects/yona,bloodybear/yona,doortts/fork-yobi,ihoneymon/yobi,brainagenet/yobi,naver/yobi,Limseunghwan/oss,oolso/yobi,doortts/fork-yobi,yona-projects/yona,ihoneymon/yobi,ahb0327/yobi,Limseunghwan/oss,oolso/yobi,yona-projects/yona,oolso/yobi,ahb0327/yobi,naver/yobi,doortts/forked-for-history,naver/yobi,doortts/forked-for-history,doortts/fork-yobi,bloodybear/yona,bloodybear/yona,doortts/forked-for-history