py311-crosshair-tool

Analyze Python code for correctness using symbolic execution

CrossHair is an analysis tool for Python that blurs the line between testing and type systems. If you have a function with type annotations and add a contract in a supported syntax, CrossHair will attempt to find counterexamples for you. CrossHair works by repeatedly calling your functions with symbolic inputs. It uses an SMT solver (a kind of theorem prover) to explore viable execution paths and find counterexamples for you. This is not a new idea; a Python approach was first described in this paper. However, to my knowledge, CrossHair is the most complete implementation: it can use symbolic reasoning for the built-in types, user-defined classes, and much of the standard library.