Publicaties

As software has become ever important in our lives, all that code needs to be of a high quality. A common way to achieve this is via software testing, where additional "test code" is written with the sole purpose of finding mistakes in the original code, or "production code". As test code has the large responsibility of ensuring qualitative software, it is critical that the test code itself is of high quality as well. However, while the quality ...

Recent research has shown that clones occur far more often in test code than in production code. This is explained by the typical template of unit test code (the setup-stimulate-verify-teardown cycle), a template which lends itself well to parameterisation of proven solutions. However, little is known on how these clones evolve over time. In this paper, we compare the evolution of clones in test code with those in production code. Based on a ...

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 ...

With the current emphasis on DevOps, automated software tests become a necessary ingredient for continuously evolving, high-quality software systems. This implies that the test code takes a significant portion of the complete code base---test to code ratios ranging from 3:1 to 2:1 are quite common. We argue that "testware" provides interesting opportunities for formal verification, especially because the system under test may serve as an oracle ...

Software clones are considered a code smell in software development. While most clones occur due to developers copy-paste behaviour, some of them arise accidentally as a symptom of coding idioms. If such accidental clones occur across projects, then they may indicate a lack of abstraction in the underlying programming language or libraries. In this research, we study accidental cross-project clones from the perspective of missing abstraction. We ...

Duplicated test code (a.k.a. test code clones) has a negative impact on test comprehension and maintenance. Moreover, the typical structure of unit test code induces structural similarity, increasing the amount of duplication. Yet, most research on software clones and clone detection tools is focused on production code, often ignoring test code. In this paper we fill this gap by comparing four different clone detection tools (NiCad, CPD, ...

The typical structure of unit test code (setup stimulate - verify - teardown) gives rise to duplicated test logic. Researchers have demonstrated the widespread use of syntactic clones in test code, yet if duplicated test code is indeed a problem, then semantic clones may be an issue as well. However, while detecting syntactic similarities can be done relatively easy, semantic similarities are more difficult to find. In this paper we present a ...

Code clones commonly occur during software evolution. They impact the effort of software development and maintenance, and therefore they need to be monitored. We present a large-scale empirical study (237 open-source Java projects maintained by 500 individuals) that investigates how the number of clones changes throughout software evolution, as well as the tendency of individual developers to introduce clones. Our results will set a ...