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  • Andy Pearce thinks this is interesting:

To me, legacy code is simply code without tests. I’ve gotten some grief for this definition. What do tests have to do with whether code is bad? To me, the answer is straightforward, and it is a point that I elaborate throughout the book:

You might think that this is severe. What about clean code? If a code base ...

From

Cover of Working Effectively with Legacy Code

Note

This is an important explanation of why tests are critical. Code without tests might still be really good code, but how do you know it’s really good code? How do you know that it’ll stay really good code?