Systematic code maturity assessment using Trail of Bits' 9-category framework. Analyzes codebase for arithmetic safety, auditing practices, access controls, complexity, decentralization, documentation, MEV risks, low-level code, and testing. Produces professional scorecard with evidence-based ratings and actionable recommendations.
property-based-testing
property-based-testing is an open-source testing skill for Claude Code and compatible agents, published by trailofbits. Its author describes it as: “Writes, reviews, and debugs property-based tests — Hypothesis, fast-check, proptest, jqwik, rapid, and Echidna or Medusa for Solidity invariants. Use whenever tests should cover a whole input domain instead of a hand-…”. The project has 6.6k stars on GitHub and is available under the CC-BY-SA-4.0 license. Add it to your setup with `/plugin marketplace add trailofbits/skills`.
What property-based-testing does
An example test asserts one point. A property asserts a rule over the whole input domain and lets the generator hunt for the counterexample. That trade is worth making when the code has an algebraic shape — an inverse, an invariant, an oracle — and not otherwise. Code with no such shape gets example tests; saying so is a valid outcome.
Installation
Add property-based-testing to your agent with:
/plugin marketplace add trailofbits/skillsAlways review a skill's source before installing it. This command comes from the skill's public repository; the linked repo is the source of truth for exact setup steps.
What's inside
The SKILL.md for property-based-testing is organised into these sections:
- Property catalog
- The two ways a property test asserts nothing
- Where to look next
- Introducing PBT to a project that lacks it
When to use it
Reach for property-based-testing when you want testing help from your agent without writing the same instructions every session. Load the skill and the agent picks it up automatically for relevant tasks.
Strengths
- Clear CC-BY-SA-4.0 license — safe to read and adapt
- Ships in trailofbits/skills, an established project with 6,646 GitHub stars
- Actively maintained (recent commits)
Topics
Frequently asked questions
- What does property-based-testing do?
- Writes, reviews, and debugs property-based tests — Hypothesis, fast-check, proptest, jqwik, rapid, and Echidna or Medusa for Solidity invariants. Use whenever tests should cover a whole input domain instead of a hand-picked list of examples: encode/decode and serialize/deserialize pairs, parsers, canonicalizers and normalizers, validators, numeric and Decimal types, comparators and sort order, data structures, and smart-contract state invariants. Also use when adding cases to an existing @given, fast-check, or proptest suite, when judging whether existing property tests assert anything real, and when a generator has shrunk a counterexample and you need to tell a wrong property from a genuine bug. Not for coverage-guided binary fuzzing (libFuzzer, AFL), mutation-testing campaigns, static analysis, benchmarking, or end-to-end UI tests.
- How do I install property-based-testing?
- Run /plugin marketplace add trailofbits/skills in your agent, then reload your skills. Review the source at https://github.com/trailofbits/skills before installing.
- Is property-based-testing free to use?
- Yes. property-based-testing is free and open source under the CC-BY-SA-4.0 license, so you can read, run, and adapt it within that license's terms.
- Where does property-based-testing come from?
- property-based-testing ships inside trailofbits/skills, a repository that contains 41 catalogued skills in total. The repository's 6,646 GitHub stars apply to that whole collection, not to this skill on its own.
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