Evaluating the efficacy of test-driven development: industrial case studies

Abstract

This paper discusses software development using the Test Driven Development (TDD) methodology in two different environments (Windows and MSN divisions) at Microsoft. In both these case studies we measure the various context, product and outcome measures to compare and evaluate the efficacy of TDD. We observed a significant increase in quality of the code (greater than two times) for projects developed using TDD compared to similar projects developed in the same organization in a non-TDD fashion. The projects also took at least 15% extra upfront time for writing the tests. Additionally, the unit tests have served as auto documentation for the code when libraries/APIs had to be used as well as for code maintenance.