# Property-Based Testing: Trail of Bits Turns Property Testing into Reusable Agent Skills

Trail of Bits' property-based-testing is a cross-language skill guide for property testing that includes smart contracts. It teaches agents to identify encoding/decoding, parsing, normalization, and contract invariants, write tests based on properties like round-trip and idempotence, and distinguish between test errors and real bugs when tests fail. Based on the official SKILL.md, plugin READMEs and market repositories, the article explains the installation of Claude Code / Codex, the `npx skills add` command, and reproducible examples such as Hypothesis.