1) This is true for YOU not necessarily for the next person, hopefully when you are rewriting the code you maintain some level of decency and leave a comment tr

1) This is true for YOU not necessarily for the next person, hopefully when you are rewriting the code you maintain some level of decency and leave a comment trail. If you optimize and clean the code there is a high chance that you end up with complex functionality packed into one liners. 2,3) If you do not have a test suite how can you reproduce the original code 1 for 1? Similar for new features. I totally agree that code (at least functionally) should always come with a test suite. If there isn't a test suite and you are planning to rewrite the code, the priority should be in writing a test suite or a black-box tester. At the minimum you should have a list of supported features that you are going to check off.