A Quantitative Comparison of Test-First and Test-Last Code in an Industrial Project

This paper presents a comparison of test-first and test-last development approaches on a customer account management software of a telecommunication company. While the management had plans for initiating a process that enforces test-first development over test-last, they also had concerns about the tradeoffs. Therefore, an exploratory case study with quantitative analysis is carried out on a pilot project where the code metrics and estimated manual inspection efforts of both approaches are compared. Our results indicate no statistical difference between the two approaches in terms of design (CK) metrics. On the other hand, we observe that test-last development yields significantly simpler code in terms of cyclomatic complexity and less (though not significant) manual inspection effort. Hence, our initial results indicate no superiority of test-first over test-last development in the described industrial context.