Comprehensive testing strategies for Rust including property-based testing with proptest, fuzz testing with cargo-fuzz, benchmark testing with Criterion, contract testing for traits, and Miri for undefined behavior detection. Use when writing tests, ensuring code correctness, detecting edge cases, or measuring performance.
Build web components using Custom Elements v1 API with Declarative Shadow DOM, attribute-driven state, handleEvent pattern, and zero DOM selection. Use when creating custom elements, extending built-in HTML elements, or implementing component-based architecture. NO querySelector, NO innerHTML, NO external libraries - pure web platform APIs only.