Automated support for repairing input-model faults

Model transforms are a class of applications that convert a model to another model or text. The inputs to such transforms are often large and complex; therefore, faults in the models that cause a transformation to generate incorrect output can be difficult to identify and fix. In previous work, we presented an approach that uses dynamic tainting to help locate input-model faults. In this paper, we present techniques to assist with repairing input-model faults. Our approach collects runtime information for the failing transformation, and computes repair actions that are targeted toward fixing the immediate cause of the failure. In many cases, these repair actions result in the generation of the correct output. In other cases, the initial fix can be incomplete, with the input model requiring further repairs. To address this, we present a pattern-analysis technique that identifies correct output fragments that are similar to the incorrect fragment and, based on the taint information associated with such fragments, computes additional repair actions. We present the results of empirical studies, conducted using real model transforms, which illustrate the applicability and effectiveness of our approach for repairing different types of faults.