What would you do when you are about to add some new features to a large (and dirty) codebase which has virtually *NO* unit-testing code?

Question

Martin Fowler says that we should do refactoring before adding new features (given that the original program is not well-structured).

So we all want to refactor this

Answer 1

Let me recommend the book Working effectively with legacy code by Michael Feathers. It contains a lot of realistic examples and shows good techniques for tackling the legacy code beast.

Answer 2

My suggestion would be that you touch as little as possible and add what you need. I have found that it is best to leave well enough alone, especially if you are on a tight deadline.

If you had had unit tests, that would be a different story, but when you change code it can be like touching a spider web. Changing one thing can affect everything else.