Gabriela Sampaio’s research while affiliated with Imperial College London and other places

A product line is an approach for systematically managing configuration options of customizable systems, usually by means of features. Products are generated for configurations consisting of selected features. Product-line evolution can lead to unintended changes to product behavior. We illustrate that updating configurations after product-line evolution requires decisions of both, domain engineers responsible for product-line evolution as well as application engineers responsible for configurations. The challenge is that domain and application engineers might not be able to interact with each other. We propose a formal foundation and a methodology that enables domain engineers to guide application engineers through configuration evolution by sharing knowledge on product-line evolution and by defining automatic update operations for configurations. As an effect, we enable knowledge transfer between those engineers without the need for interactions. We evaluate our methodology on four large-scale industrial product lines. The results of the qualitative evaluation indicate that our method is flexible enough for real-world product-line evolution. The quantitative evaluation indicates that we detect product behavior changes for up to $55.3\%$ 55.3 % of the configurations which would not have been detected using existing methods.

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.

A key challenge developers might face when evolving a product line is not to inadvertently affect users of existing products. In refactoring and conservative extension scenarios, we can avoid this problem by checking for behavior preservation, either by testing the generated products or by using formal theories. Product line refinement theories support that by requiring behavior preservation for all existing products. However, in many evolution scenarios, such as bug fixing, there is a high chance that only some of the products are refined. To support developers in these and other non full-refinement situations, we define a theory of partial product line refinement that helps to precisely understand which products should not be affected by an evolution scenario. This provides a kind of impact analysis that could, for example, reduce test effort, since products not affected do not need to be tested. Additionally, we formally derive a catalog of eight partial refinement templates that capture evolution scenarios, and associated preconditions, not covered before. Finally, by analyzing 79218 commits from the Linux repository, we find evidence that the proposed templates could cover a number of practical evolution scenarios.