ASketch: a sketching framework for Alloy

Alloy is a declarative modeling language that supports first-order logic with transitive closure. Alloy has been used in a variety of domains to model software systems and find design deficiencies. However, it is often challenging to make an Alloy model correct or to debug a faulty Alloy model. ASketch is a sketching/synthesis technique that can help users write correct Alloy models. ASketch allows users to provide a partial Alloy model with holes, a generator that specifies candidate fragments to be considered for each hole, and a set of tests that capture the desired model properties. Then, the tool completes the holes such that all tests for the completed model pass. ASketch uses tests written for the recently introduced AUnit framework, which provides a foundation of testing (unit tests, test execution, and model coverage) for Alloy models in the spirit of traditional unit testing. This paper describes our Java implementation of ASketch, which is a command-line tool, released as an open-source project on GitHub. Our experimental results show that ASketch can handle partial Alloy models with multiple holes and a large search space. The demo video for ASketch can be found at https://youtu.be/T5NIVsV329E.