As a fine-grained defect detection technique, unit testing introduces a strong dependency on the structure of the code. Accordingly, test coevolution forms an additional burden on the software developer which can be tempered by writing tests in a manner that makes them easier to change. Fortunately, we are able to concretely express what a good test is by exploiting the specific principles underlying unit testing. Analogous to the concept of code smells, violations of these principles are termed test smells. In this paper, we clarify the structural deficiencies encapsulated in test smells by formalizing core test concepts and their characteristics. To support the detection of two such test smells, General Fixture and Eager Test, we propose a set of metrics defined in terms of unit test concepts. We compare their detection effectiveness using manual inspection and through a comparison with human reviewing. Although the latter is the traditional means for test quality assurance, our results indicate it is not a reliable means for test smell detection. This work thus stresses the need for a more reliable detection mechanism and provides an initial contribution through the validation of test smell metrics.

Test code, just like any other code we write, erodes when frequently changed. As such, refactoring, which has been shown to impact maintainability and comprehensibility, can be part of a solution to counter this erosion. We propose a metric-based heuristical approach, which allows to rank occurrences of so-called test smells (i.e. symptoms of poorly designed tests) according to their relative significance. This ranking can subsequently be used to start refactoring. Through an open-source case study, ArgoUML, we demonstrate that we are able to identify those test cases who violate unit test criteria

During initial program comprehension, software engineers could benefit from knowing the most need-to-be-understood classes in the system under study in order to kick-start their software reconnaissance. Previously we have used Webmining techniques on runtime trace data to identify these important classes. Here, we reprise this Webmining technique and make a thorough comparison of its effectiveness when collecting static information of the software system under study. Apache Ant and Jakarta JMeter, two medium-scale open source Java software systems, serve as case studies. From publicly available developers notes we conclude that the Webmining technique in combination with dynamic analysis provides the best results with a level of recall of 90% when comparing with the developers' opinion