eXtreme programming is an Agile software development methodologies. It involves extremely short incremental release cycles, early and frequent testing, heavy use of design refactoring, and pair programming. This article proposes a process model called “ordered incremental testing” where guidance on test order is provided. Testing is conducted iteratively with very short iteration cycles as a single class is developed. Although early and frequent testing is very important, there is little guidance about specifics of the testing process.