Partially safe evolution of software product lines

Software Product Lines allow the automatic generation of related products built with reusable artefacts. In this context, developers may need to perform changes and check whether products are affected. A strategy to perform such analysis is verifying behaviour preservation through the use of formal theories. The product line refinement notion requires behaviour preservation for all existing products. Nevertheless, in evolution scenarios like bug fixes, some products intentionally have their behaviour changed. To support developers in these and other unsafe scenarios, we define a theory of partial product line refinement that helps to precisely understand which products are affected by a change. This provides a kind of impact analysis that could, for example, reduce test effort, since only affected products need to be tested. We provide properties such as compositionality, which deals with changes to a specific product line element, and general properties to support developers when safe and partially safe scenarios are combined. We also define a set of transformation templates, which are classified according to their compatibility to specific types of product lines. To evaluate our work, we analyse two product lines: Linux and Soletta, to discover if our templates could be helpful in evolving these systems. (C) 2019 Elsevier Inc. All rights reserved.