property-based-testing

Property-based testing verifies invariants across generated inputs to automatically discover edge cases. You define properties like roundtrip or idempotence, and the framework checks them against hundreds of inputs.

Use property-based testing to verify serialization roundtrips by defining decode(encode(x)) == x as a property. The framework generates diverse inputs to validate this invariant across your entire input domain.

Property-based testing supports multiple libraries including Hypothesis for Python, fast-check for JavaScript, Proptest for Rust, and jqwik for Java, applying invariants across various codebases and languages.

Common property-based testing patterns include roundtrip validation for serialization, idempotence for normalization, and invariant checking for pure functions. These patterns detect edge cases and improve test coverage.

Shift to property-based testing when example-based tests miss edge cases or fail to cover invariants comprehensively. It automatically generates inputs to test conditions like serialization roundtrips and normalization idempotence.

Use a property catalog to organize invariants and test strategies for serialization, normalization, and pure functions. This structure helps manage property-based testing across multiple codebases and languages.