对于调试目标和跟踪测试过程，你会想要大体知道已经运行了哪些测试用例，以及它们的结果是什么。

For debugging purposes and for tracing the progress of testing, you want to know at a glance what tests cases have been run and what the results were.

youdao

But for the next week or two when you're writing programs, at least for the first time, generally if you're trying Scratch to debug them like you might have been trying to troubleshoot Scratch, you're probably going to reason - through it by looking through the your code -- -- top to bottom, maybe engage a staff member for help -- but your friend will also be printf.

但是，在接下来的一两周内，当你们写程序的时候，或至少在第一次写的时候，通常如果你在调试程序,就像你们可能已经试着调试过,你们或许是通过查看你们的代码,来推断你们的程序-,从头到尾，可能还需要别人的帮忙-,但是你的朋友也将要打印输出。

哈佛公开课 - 计算机科学课程节选