Although Agile methodologies have been in use since the late 1990’s it is still rare to find more than anecdotal evidence for how well they really work. In evaluating whether to use agile methods, engineers have very little on which to base a judgment unless they happen to have some direct knowledge of an agile software project. This paper describes a developer-led conversion to agile methods where the software team themselves recorded detailed data throughout the project. They used a very simple home-made unit test framework for development in C. Since the close of that project the senior members of the software team built a better unit test framework intended for doing agile software development in C. This paper gives a brief overview of the Catsrunner framework (CATS = C Automated Test System).