# Retrofitting unit tests > ## Abstract ## Abstract > In this paper we describe techniques that we have found helpful for adding [unit tests](https://wiki.g15e.com/pages/Unit%20test.txt) to existing code that has been written without tests. The paper presents some common coding practices that make unit tests hard to retrofit, and why. For each practice we suggest minimal [refactorings](https://wiki.g15e.com/pages/Refactoring.txt) to open up the code for testing. ## See also -