The correlation between code coverage, cyclomatic complexity and fault frequency

Abstract: The quality of software gets more and more important as software is introduced to systems that are important to the infrastructure of modern society. This thesis studies one such code base developed at Ericsson AB, that is a vital piece of software for our infrastructure. With an increased need for quality in software, it is important that we have quantifiable metrics that can be used to steer the development of software in a direction that leads to fewer faults. We look at the software metrics cyclomatic complexity and variations of code coverageand analyse how these metrics correlate to faults in the code. We find that code coverage has a weak negative correlation at best, but can have a weak positive correlation at worst (such that faults increase as coverage increases). The cyclomatic complexity metric has not been found to have any correlation at all to software faults.