Changes and bugs — Mining and predicting development activities

Software development results in a huge amount of data: changes to source code are recorded in version archives, bugs are reported to issue tracking systems, and communications are archived in e-mails and newsgroups. We present techniques for mining version archives and bug databases to understand and support software development. First, we introduce the concept of co-addition of method calls, which we use to identify patterns that describe how methods should be called. We use dynamic analysis to validate these patterns and identify violations. The co-addition of method calls can also detect cross-cutting changes, which are an indicator for concerns that could have been realized as aspects in aspect-oriented programming. Second, we present techniques to build models that can successfully predict the most defect-prone parts of large-scale industrial software, in our experiments Windows Server 2003. This helps managers to allocate resources for quality assurance to those parts of a system that are expected to have most defects. The proposed measures on dependency graphs outperformed traditional complexity metrics. In addition, we found empirical evidence for a domino effect, i.e., depending on defect-prone binaries increases the chances of having defects.