Are the Clients of Flawed Classes (Also) Defect Prone?

Design flaws are those characteristics of design entities (e.g., methods, classes) which make them harder to maintain. Existing studies show that classes revealing particular design flaws are more change and defect prone than the other classes. Since various collaborations are found among the instances of classes, classes are not isolated within the source code of object-oriented systems. In this paper we investigate if classes using classes revealing design flaws are more defect prone than classes which do not use classes revealing design flaws. We detect four design flaws in three releases of Eclipse and investigate the relation between classes that use/do not use flawed classes and defects. The results show that classes that use flawed classes are defect prone and this does not depend on the number of the used flawed classes. This findings show a new type of correlation between design flaws and defects, bringing evidence related to an increased likelihood of exhibiting defects for classes that use classes revealing design flaws. Based on the provided evidence, practitioners are advised once again about the negative impact design flaws have at a source code level.