### Question:
GroupServiceImpl implements GroupService { @Override public boolean deleteByGroupId(Long groupId) { return groupDao.deleteByGroupId(groupId); }  @Override Group findByGroupId(Long groupId); @Override Map<Long, Group> listByGroupIdIn(List<Long> groupIds); @Override boolean insertGroup(Group group); @Override boolean updateGroup(Group group); @Override boolean incMemberNumByGroupId(Long groupId, Integer memberNum); @Override boolean decMemberNumByGroupId(Long groupId); @Override boolean deleteByGroupId(Long groupId);  }### Answer:
@Test public void deleteByGroupId() { }