property-test-writer

What problem does it solve?

Example-based test suites only cover a small subset of possible inputs, missing pathological edge cases like empty values, huge payloads, Unicode characters, and near-boundary inputs that cause production bugs. This Skill writes property-based tests that verify universal invariants hold across the entire input space, catching bugs that example tests will never find.

Core Features & Use Cases

• Multi-framework support: Generates property tests for Hypothesis (Python), fast-check (TypeScript), jqwik (Java), FsCheck (C#), proptest (Rust), and 8+ other frameworks across 7 languages.
• Key property types: Implements round-trip, idempotency, commutativity, associativity, preservation, oracle/differential, metamorphic, and stateful model-based test patterns.
• Use case: For a JSON serialization module, this Skill generates tests that verify decode(encode(x)) == x for all valid inputs, automatically shrinking any failing case to the minimal reproducible counterexample.

Quick Start

Use the property-test-writer skill to generate property-based tests for your serialization module that verify round-trip invariants hold for every valid input.