Generating Metamodel Instances Satisfying Coverage Criteria via SMT Solving

One of the challenges for using metamodels in Model Driven Engineering is to automatically generate metamodel instances. Each instance should satisfy many constraints defined by a metamodel. Such instances can then be used for verifying or validating metamodels. Recent studies have already shown that this can be tackled by using SAT/SMT solvers. However, such instance generation does not take coverage criteria into account, and instances satisfying specified coverage criteria could be useful for testing model transformation. In this paper, we present an approach consisting of two techniques for coverage oriented metamodel instance generation. The first technique realises the standard coverage criteria defined for UML class diagrams, while the second technique focuses on generating instances satisfying graph-based criteria. With our approach, both kinds of criteria are translated to SMT formulas which are then investigated by an SMT solver. Each successful assignment is then interpreted as a metamodel instance that provably satisfies a coverage criteria or a graph property. We have already integrated this approach into our existing tool to demonstrate the feasibility.