Assisted coverage closure

Malfunction of safety-critical systems may cause damage to people and the environment. Software within those systems is rigorously designed and verified according to domain specific guidance, such as ISO26262 for automotive safety. This paper describes academic and industrial co-operation in tool development to support one of the most stringent of the requirements --- achieving full code coverage in requirements-driven testing. We present a verification workflow supported by a tool that integrates the coverage measurement tool RapiCover with the test-vector generator FShell. The tool assists closing the coverage gap by providing the engineer with test vectors that help in debugging coverage-related code quality issues and creating new test cases, as well as justifying the presence of unreachable parts of the code in order to finally achieve full effective coverage according to the required criteria. We illustrate the tool's practical utility on automotive industry benchmarks. It generates 8 times more MC/DC coverage than random search.