Efficient specification-based testing using incremental techniques
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As software systems grow in complexity, the need for efficient automated techniques for design, testing and verification becomes more and more critical. Specification-based testing provides an effective approach for checking the correctness of software in general. Constraint-based analysis using specifications enables checking various rich properties by automating generation of test inputs. However, as specifications get more complex, existing analyses face a scalability problem due to state explosion. This dissertation introduces a novel approach to analyze declarative specifications incrementally; presents a constraint prioritization and partitioning methodology to enable efficient incremental analyses; defines a suite of optimizations to improve the analyses further; introduces a novel approach for testing software product lines; and provides an experimental evaluation that shows the feasibility and scalability of the approach. The key insight behind the incremental technique is declarative slicing, which is a new class of optimizations. The optimizations are inspired by traditional program slicing for imperative languages but are applicable to analyzable declarative languages, in general, and Alloy, in particular. We introduce a novel algorithm for slicing declarative models. Given an Alloy model, our fully automatic tool, Kato, partitions the model into a base slice and a derived slice using constraint prioritization. As opposed to the conventional use of the Alloy Analyzer, where models are analyzed as a whole, we perform analysis incrementally, i.e., using several steps. A satisfying solution to the base slice is systematically extended to generate a solution for the entire model, while unsatisfiability of the base implies unsatisfiability of the entire model. We show how our incremental technique enables different analysis tools and solvers to be used in synergy to further optimize our approach. Compared to the conventional use of the Alloy Analyzer, this means even more overall performance enhancements for solving declarative models. Incremental analyses have a natural application in the software product line domain. A product line is a family of programs built from features that are increments in program functionality. Given properties of features as firstorder logic formulas, we automatically generate test inputs for each product in a product line. We show how to map a formula that specifies a feature into a transformation that defines incremental refinement of test suites. Our experiments using different data structure product lines show that our approach can provide an order of magnitude speed-up over conventional techniques.