Testing Global Constraints

TL;DR

This paper introduces a Java library for testing the correctness of constraint implementations in CP solvers, aiding developers in bug detection and ensuring solver reliability.

Contribution

It provides a novel testing library for JVM-based CP solvers, enabling automated correctness checks and debugging support for constraint implementations.

Findings

Library successfully detects incorrect constraint implementations

Facilitates continuous integration testing for CP solvers

Helps identify minimal violating instances for debugging

Abstract

Every Constraint Programming (CP) solver exposes a library of constraints for solving combinatorial problems. In order to be useful, CP solvers need to be bug-free. Therefore the testing of the solver is crucial to make developers and users confident. We present a Java library allowing any JVM based solver to test that the implementations of the individual constraints are correct. The library can be used in a test suite executed in a continuous integration tool or it can also be used to discover minimalist instances violating some properties (arc-consistency, etc) in order to help the developer to identify the origin of the problem using standard debuggers.