Computation of the minimal set of paths for observability-based statement coverage

Existing coverage-based validation methods guarantee the execution of a certain percentage of the program code under test, however they do not generally verify whether the statements executed have any influence on the program’s output. Motivated by an observability coverage metric for embedded software we propose a coverage-directed path generation method. In this method, a program statement is considered covered not only if it belongs to the executed path, but also if its execution has influence in some output. The paths are generated by finding the longest path in a tree representing the possible execution paths of the program. Generated paths are then validated to check for feasibility. If a feasible path is found, then we determine and mark the statements actually observed using the computed inputs for exercising the path. If unfeasible, we search for the next longest path. If the desired level of coverage was not obtained yet then a new tree is built. This new tree will reflect the coverage obtained so far and also the information gathered when checking the feasibility of previous paths. We present results that demonstrate the effectiveness of this methodology.