  In this paper, we investigate the effect of TDD, as compared to a non-TDD
approach, as well as its retainment (or retention) over a time span of (about)
six months. To pursue these objectives, we conducted a (quantitative)
longitudinal cohort study with 30 novice developers (i.e., third-year
undergraduate students in Computer Science). We observed that TDD affects
neither the external quality of software products nor developers' productivity.
However, we observed that the participants applying TDD produced significantly
more tests, with a higher fault-detection capability than those using a non-TDD
approach. As for the retainment of TDD, we found that TDD is retained by novice
developers for at least six months.
