{"categories":[{"label":"Testing","url":"https://skillfed.io/packages/category/software-development-testing/3"},{"label":"Quality Assurance","url":"https://skillfed.io/packages/category/software-development-quality-assurance/2"}],"enrichment":{"capability":"CrossHair uses symbolic execution and SMT solving to find counterexamples to type-annotated functions with contracts, and can generate unit tests or detect behavioral differences between implementations.","skillfed_tags":["symbolic-execution","contract-verification","smt-solver"],"use_cases":["Find edge cases and counterexamples in functions with type annotations and contracts before they reach production","Generate test cases automatically by exploring symbolic execution paths through your code","Verify that refactored or optimized functions behave identically to their original implementations","Use as a Hypothesis backend for property-based testing with symbolic reasoning","Catch off-by-one errors, null-pointer-like issues, and invariant violations in class methods"],"what_it_does":"CrossHair is a symbolic execution and theorem-proving tool for Python that bridges testing and type systems. You annotate functions with type hints and optional contracts (preconditions, postconditions, invariants), and CrossHair explores execution paths using an SMT solver to find inputs that violate those contracts\u2014essentially automated counterexample generation. It works by repeatedly calling your functions with symbolic inputs, tracking constraints, and asking the solver whether any path can violate your specifications.\n\nBeyond contract checking, CrossHair can generate unit tests by exploring code paths and detecting behavioral differences between function implementations. It integrates with Hypothesis as an optional backend and offers IDE plugins for VS Code and PyCharm. The tool targets developers who want stronger correctness guarantees than traditional testing alone, particularly for functions with clear specifications. Runtime dependencies include z3-solver (the SMT engine), typing-inspect, pygls (for language server protocol), and typeshed-client.","worth_installing":"Yes, if you work with type-annotated Python and want automated counterexample detection beyond traditional testing. The active maintenance, broad Python version support, and zero known vulnerabilities make it safe to adopt. Install friction is moderate due to z3-solver's compilation requirements, but prebuilt wheels are available. Best suited for projects where correctness is critical and you're willing to write contracts alongside type hints."},"id":"crosshair-tool","links":{"html":"https://skillfed.io/packages/crosshair-tool","md":"https://skillfed.io/packages/crosshair-tool.md","pypi":"https://pypi.org/project/crosshair-tool/"},"maintenance":{"status":"active"},"meta":{"latest_release":"2026-07-21","license_spdx":null,"license_treatment":"permissive","name":"crosshair-tool","python_support":"supports_current","summary":"Analyze Python code for correctness using symbolic execution."},"popularity":{"monthly_downloads":417304,"position":6818,"tier":"top_15000"},"security":{"n_vulnerabilities":0},"version":"0.0.109"}