What problem does it solve? Example-based unit tests only catch inputs the author thought to write, leaving bugs in parsers, serializers, and normalization logic undiscovered. This Skill generates property-based tests that check invariants across thousands of generated inputs and shrink failures to minimal counterexamples. ## Core Features & Use Cases - Invariant-Driven Test Generation: Writes property tests for round-trip, idempotence, invariant preservation, algebraic law, and metamorphic relation shapes during TDD's white-box pass. - Multi-Language Tool Detection: Detects the project manifest (pyproject.toml, package.json, pom.xml, Cargo.toml, go.mod) and selects Hypothesis, fast-check, jqwik, proptest, or Go's native fuzzing accordingly. - Vacuous Property Detection: Catches anti-patterns like always-true assertions and properties that re-derive the implementation, integrating with test-quality-reviewer's 3i check. - Use Case: While test-driving a new encode/decode pair, invoke this Skill to generate a Hypothesis round-trip property; when it fails, commit the shrunk counterexample as a permanent regression test. ## Quick Start Use the property-based-testing skill to write property tests for my parse and serialize functions in this Python project.
