property-based-testing

Property-based testing replaces brittle example-based tests with input-driven validation, generating randomized inputs to detect edge cases and verify invariants for more robust software. It validates that specific properties hold true across a wide range of generated data.

Design property-based tests by defining clear properties and appropriate input strategies for serialization, normalization, and validation. Use Property-Driven Development to specify roundtrip properties and invariants before writing the actual implementation code.

Yes, property-based testing supports smart contracts written in Solidity and Vyper. It guides the application of invariant testing for contract validation using specialized tools like Echidna or Medusa to ensure contract robustness against unexpected states.

Yes, the guidance covers practical use of libraries like Hypothesis for Python and fast-check for JavaScript. It provides executable patterns and input strategies across multiple languages including Rust, Go, Java, and Haskell.

Review existing property-based tests to surface tautologies, vacuous tests, and weak assertions. This process identifies tests that always pass regardless of input quality, ensuring your input strategies and properties genuinely validate logic.