Safe Evolution of Software Product Lines: Feature Extraction Scenarios

Software Product Lines can improve productivity and product quality, but product line maintenance is not simple, since a single change can impact several products. In many situations, it is desirable to provide some assurance that we can safely change a SPL in the sense that the behaviour of existing products is preserved. Developers can rely on previously proposed safe evolution notions, by means of transformation templates to ensure safe evolution. However, the existing templates were only applied in scenarios where a product line expands, and have not been evaluated in the context of extracting features from existing code. Therefore, we conducted a study using an industrial system developed in Java with 400 KLOC. This study revealed the need for new templates to address feature extraction scenarios, as well as improving the existing templates notation to address more expressive mappings between features and code assets. As a result of this study, we successfully extracted a product line from this existing system using the proposed templates, and also found evidence that the new templates can help to prevent defects during product line evolution.