Observations on the connectedness between requirements-to-code traces and calling relationships for trace validation

Traces between requirements and code reveal where requirements are implemented. Such traces are essential for code understanding and change management. Unfortunately, the handling of traces is highly error prone, in part due to the informal nature of requirements. This paper discusses observations on the connectedness between requirements-to-code traces and calling relationships within the source code. These observations are based on the empirical evaluation of four case study systems covering 150 KLOC and 59 sample requirements. We found that certain patterns of connectedness have high or low likelihoods of occurring. These patterns can thus be used to confirm or reject existing traceability - hence they are useful for validating requirements-to-code traces.