String secondMentionedUserName = "jk1";
when(userDao.getByUsername(firstMentionedUserName)).thenReturn(null);
when(userDao.getByUsername(secondMentionedUserName)).thenReturn(null);
String notProcessedSource = format(MENTIONING_TEMPLATE, firstMentionedUserName, secondMentionedUserName);
MentionedUsers mentionedUsers = mock(MentionedUsers.class);
when(mentionedUsers.extractAllMentionedUsers(notProcessedSource))
.thenReturn(asSet(firstMentionedUserName, secondMentionedUserName));
String actualAfterProcess = userService.processUserBbCodesInPost(notProcessedSource);
String msgWithNotFoundUsers = format(MENTIONING_MESSAGE_WHEN_USER_NOT_FOUND, firstMentionedUserName,