If you have no tests and cruddy code, then you should probably throw it away and start again because you'll have to do all the testing, as opposed to if you have cruddy code with many tests.
如果你有一堆乱七八糟代码且又没有,那么你最好是们从头开始,否则你就得重新做所有。反,如果你有一堆乱七八糟代码同时还有很多话,情况就不一样了。