Last updated on Monday, October 06, 2025
@article{VanBladel2021JSS,
author = {Brent {van Bladel} and Serge Demeyer},
journal = {Journal of Systems and Software},
month = jun,
pages = {110940},
title = {A comparative study of test code clones and
production code clones},
volume = {176},
year = {2021},
abstract = {Clones are one of the most widespread code smells,
known to negatively affect the evolution of software
systems. While there is a large body of research on
detecting, managing, and refactoring clones in
production code, clones in test code are often
neglected in today's literature. In this paper we
provide empirical evidence that further research on
clones in test code is warranted. By analysing the
clones in five representative open-source systems and
comparing production code clones to test code clones,
we observe that test code contains twice as many
clones as production code. A detailed analysis
reveals that most test clones are of Type II and Type
III, and that many tests are duplicated multiple
times with slight modifications. Moreover, current
clone detection tools suffer from false negatives,
and that this occurs more frequently in test code
than in production code (NiCad = 76\%, CPD = 90\%,
iClones = 12\%). So even from a tools perspective,
specific fine-tuning for test code is needed.},
annote = {internationaljournal},
doi = {10.1016/j.jss.2021.110940},
}