Unit testing as a teaching tool in higher education

Unit testing in the programming world has had a profound impact in the way modern complex systems are developed. Many Open Source and Free Software projects encourage (and in some cases, mandate) the use of unit tests for new code submissions, and many software companies around the world have incorporated unit testing as part of their standard developing practices. And although not all software engineers use them, very few (if at all) object their use. However, there is almost no research available pertaining the use of unit tests as a teaching tool in introductory programming courses. I have been teaching introductory programming courses in the Computer Sciences program at the Sciences Faculty in the National Autonomous University of Mexico for almost ten years, and since 2013 I have been using unit testing as a teaching tool in those courses. The intent of this paper is to discuss the results of this experience.