Property Based Testing · alialavia bundle Find genuine property-based tests for existing code, design new code so properties hold by construction, and diagnose property-test failures — always contract-first, reading the implementation only after properties have been designed. Use this skill whenever the user asks for property-based tests, PBT, QuickCheck-style tests, invariant tests, generative tests, or fuzz tests, in any language (Python/Hypothesis, TypeScript/fast-check, Rust/proptest, Haskell/QuickCheck, Scala/ScalaCheck, etc.). Also use it whenever the task mentions properties, invariants, oracles, generators, arbitraries, shrinking, stateful/model-based testing, or a property test that is failing — even if the user doesn't say "property-based" explicitly. Pair this skill with the library-specific skill (pbt-hypothesis, pbt-fast-check, etc.) when one is available — this skill handles property discovery, design, and failure interpretation; the library skill handles syntax, strategies/arbitraries, and ecosystem-specific patterns. Without this skil
