改变了before-each和after-each中对数据库的清除，改为在before-each中清除。因为如果测试失败after-each不会运行
改变了before-each和after-each中对数据库的清除，改为在before-each中清除。因为如果测试失败after-each不会运行
before fix SPIKE_chat
merge fixes of All-done-waiter and DEBUG in SPIKE_chat
代码讲解前更新
Fix conflict