Tool-Supported Structural Coverage Analysis for DO-178C Compliant Software

Software developed according to DO-178C Level A has to undergo extremely rigorous structural coverage analysis to ensure that the code has been adequately exercised during requirements-based testing. The goal of structural coverage analysis is either to show that the requirements-based tests are adequate, or to provide analysis data, which leads to a refinement of the tests. This paper focuses on two particular issues of structural coverage analysis, namely source-code-to-object-code traceability analysis and data coupling and control coupling analysis, both of which have been challenging in the past due to little tool support. We present details of two tools: the RT-Tester Source-Code-To-Object-Code Traceability Analyzer (RTT-STO) and the RT-Tester Data & Control Coupling Analyzer (RTT-DCC), which we have developed for the low-level verification of an Airbus avionic control system, and discuss our practical experiences with tool-supported structural coverage analysis. Importantly, the verification workflow associated with these tools has been accepted by the certification authorities for DAL-A.