Don't mix refactorings with behavior changes - Code with Jason

Probably the biggest reason not to mix refactorings with behavior changes is that it makes it too easy to make a mistake.When you look at the diff between the before and after versions of a piece of code, it’s not always obvious what the implications of that change are going to be. The less obvious the implications are, the more opportunity there is for a bug to slip through.When you mix behavior changes with refactorings, the behavior change and the refactoring obscure each other, often making the change substantially harder to understand and allowing for a much greater opportunity for bugs to slip through.Mixing refactorings with behavior changes also requires you to make your deployment deltas (i.e. the amount of change being deployed) bigger. The bigger the delta, the greater the risk.