On MC/DC and implementation structure: An empirical study

In civil avionics, obtaining DO-178B certification for highly critical airborne software requires that the adequacy of the code testing effort be measured using a structural coverage criterion known as Modified Condition and Decision Coverage (MC/DC). We hypothesized that the effectiveness of the MC/DC metric is highly sensitive to the structure of the implementation and can therefore be problematic as a test adequacy criterion. We tested this hypothesis by evaluating the fault-finding ability of MC/DC-adequate test suites on five industrial systems (flight guidance and display management). For each system, we created two versions of the implementations-implementations with and without expression folding (i.e., inlining).