property-based-testing SKILL.md skillA
property-based-testing from trailofbits/skills is an agent skill: a SKILL.md folder an AI agent loads when a task calls for it.
mdr add trailofbits/skills/property-based-testing@git:20260817.04b2411Pins git:20260817.04b2411 in mdr.lock. Pin the fingerprint instead.
- Audit grade
- A, 17 of 17 checks passed
- Kind
- SKILL.md skill
- Repository
- trailofbits/skills
- Path
plugins/property-based-testing/skills/property-based-testing/SKILL.md- Versions recorded
- 3
- Latest version
- git:20260817.04b2411, committed Aug 17, 2026
- First version recorded
- Jan 14, 2026
- Size
- 4,306 bytes
- Repository stars
- 8,043
- License
- CC-BY-SA-4.0
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…
Collected from public GitHub. Every version is saved exactly as it was and never changes. Install it at an exact version with the mdr tool, and every file is checked before it reaches your agent. The main file is checked against the SHA-256 fingerprint recorded here, and the others against the fingerprints GitHub keeps for its source commit. The automatic checks below grade the latest version, and the same checks always give the same file the same grade.
What the file says
# Property-Based Testing 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. Check first whether the shape is missing or merely buried. A calculation wrapped in I/O, a string built by concatenation, an in-place mutation — each has a property and no seam to assert it through. See [references/refactoring.md](references/refactoring.md) before concluding there is nothing to assert. ## Property catalog | Property | Formula | Where it applies | |---|---|---| | Roundtrip | `decode(encode(x)) == x` | Serialization, conversion pairs | | Inverse | `f(g(x)) == x` | encrypt/decrypt, compress/decompress | | Oracle | `new(x) == reference(x)` | Optimization, refactoring, reimplementation | | Idempotence | `f(f(x)) == f(x)` | Normalization, formatting, sorting | | Invariant | Holds before and after | Any transformation, contract state | …
Read the whole file at its exact version.
How to install
mdr add trailofbits/skills/property-based-testing@sha256:9448cacb65c6237aThe line at the top of this page pins the label git:20260817.04b2411, which is what most people want. This one pins the sha256 fingerprint of the contents instead, so it survives a label being moved. Either way the exact version is written to mdr.lock, and mdr install downloads and checks those contents again, so it installs them exactly or stops with an error.
[](https://markdownregistry.com/a/art_culkvv3com57yspd)
3 badge image fetches in 30 days. What the badge shows.
Versions
The registry has recorded 3 versions of this file, between Jan 14, 2026 and Aug 17, 2026, about one every 107 days.
| version | committed | commit | size | audit | |
|---|---|---|---|---|---|
| git:20260817.04b2411 latest | 2026-08-17 | 04b2411 | 4,306 B | A | view · diff |
| git:20260211.57a837d | 2026-02-11 | 57a837d | 6,084 B | A | view · diff |
| git:20260114.695119c | 2026-01-14 | 695119c | 5,087 B | A | view |
Audit of the latest version
- pass: Frontmatter block present
- pass: Frontmatter declares a name
- pass: Frontmatter declares a description
- pass: Size between 200 bytes and 200 KB (4306 bytes)
- pass: No zero-width or bidi control characters
- pass: No instruction hidden inside an HTML comment
- pass: No link to an exfiltration or paste host
- pass: No credential-shaped string
- pass: No instruction to send local credentials anywhere
- pass: No text hidden with inline styles
- pass: No prompt-injection phrasing
- pass: No curl or wget piped into a shell
- pass: No recursive delete of root, home or parent
- pass: No instruction to read or print local credentials
- pass: No base64 blob over 200 characters
- pass: No link to a raw IP address
- pass: No script tag
Source
trailofbits/skills · 8,043 stars · license CC-BY-SA-4.0 · pushed 2026-11-06 · branch main
API
GET https://markdownregistry.com/api/v1/artifacts/art_culkvv3com57yspd GET https://markdownregistry.com/api/v1/resolve?ref=trailofbits/skills/property-based-testing GET https://markdownregistry.com/api/v1/blob/9448cacb65c6237a7c22dc59602667177ecae405524079ae9ff92240590b995a
Your AI assistant does the legwork. You hear about the deals worth your word. Hand yours the standing instructions at modelranch.com and it joins the network that reads files like this one.
Guides: the SKILL.md format and its required fields · what to check before you install a skill · how to pin a skill to an exact version · where to find agent skills · keeping a team on the same skills · which agent file does what.
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