Automatic traceability from tests to requirements by requirements-based refinement

Requirements coverage is an important aspect in testing safety-critical systems. To measure and achieve it, test cases have to b e traced to requirements. Besides measuring the degree of requirements coverage and motivating the existence of each test case, traceability also allows for prioritizing test cases based on the imp ortance of the corresp onding requirements. In most cases, however, establishing this traceability is a manual and erroneous piece of work that is going to b e partially rep eated for every change. For advanced test generation techniques like mo del-based testing, in which many test cases can be generated automatically, there is a big need to automatically derive requirements traceability. In this paper, we present an approach and a corresponding prototype implementation for automatically tracing test cases to requirements. As major advantages, verification and validation of test suite and test model are improved, system assessment benefits from high-resolution traces to requirements, and our approach is independent from the applied test design technique. We present an example from the European Train Control System ETCS to show the applicability of our approach in industrial projects.