Understanding Where Requirements are Implemented The Relationship between Requirements Traces and Method Calls in Code

Trace links between requirements and code reveal where requirements are implemented. Such trace links are essential for code understanding and change management. The lack thereof is often cited as a key reason for software engineering failure. Unfortunately, the creation and maintenance of requirements-to-code traces remains a largely manual and error prone task due to the informal nature of requirements. This paper demonstrates that reasoning about requirements-to-code traces can be done, in part, by considering the calling relationships within the source code (call graph). We observed that requirements-to-code traces form regions along calling dependencies. Better knowledge about these regions has several direct benefits. For example, erroneous traces become detectable if a method inside a region does not trace to a requirement. Or, a missing trace (incompleteness) can be identified. Knowledge of requirement regions can also be used to help guide developers in establishing requirements-to-code traces in a more efficient manner. This paper discusses requirement regions and sketches their benefits. Keywords-requirements, call tree, traces, feature location