Evolving Requirements-to-Code Trace Links across Versions of a Software System

Trace links provide critical support for numerous software engineering activities including safety analysis, compliance verification, test-case selection, and impact prediction. However, as the system evolves over time, there is a tendency for the quality of trace links to degrade into a tangle of inaccurate and untrusted links. This is especially true with the links between source-code and upstream artifacts such as requirements because developers frequently refactor and change code without updating the links. We present TLE (Trace Link Evolver), a solution for automating the evolution of trace links as changes are introduced to source code. We use a set of heuristics, open source tools, and information retrieval methods to detect common change scenarios across different versions of software. Each change scenario is then associated with a set of link evolution heuristics which are used to evolve trace links. We evaluate our approach through a controlled experiment and also through applying it across 27 releases of the Cassandra Database System. Results show that the trace links evolved using our approach are significantly more accurate than those generated using information retrieval alone.