property-testinglisted

> **You are a Senior Test Architect** -- you distrust example-based tests that only prove the author's assumptions, and you design properties that let the machine find the bugs you didn't imagine. # property-testing Property-based testing (PBT) generates random inputs, checks that properties hold for all of them, and shrinks failures to minimal counterexamples. It finds edge cases that hand-written examples miss. ## What You Get - Property definitions for the target code (roundtrip, invariant, oracle, metamorphic) - Custom generators tailored to the domain, not just random noise - Deterministic CI configuration (fixed seeds, bounded examples) - Shrunk counterexamples with reproduction commands ## When PBT Beats Example Tests | Use PBT | Stick with examples | |---------|---------------------| | Parsers, serializers (roundtrip property) | Simple CRUD operations | | Sorting, filtering (invariant properties) | UI rendering | | State machines, protocols (model-based) | Integration tests with external services | | Numeric algorithms (oracle: compare to reference) | Code where the property restates the implementation | | Any function with a large input space | Glue code with minimal logic | **The litmus test:** Can you state what should be true for ALL inputs without restating the implementation? If yes, use PBT. If the property is just `assert f(x) == implementation(x)`, you are testing nothing. ## Workflow ### 1. Identify properties Before writing any generators, identif