# Conformance Testing **Domain:** Testing / Interoperability **Doc Type:** Canonical Concept Node **Maturity:** Core Design Principle **Related:** [[wiki/Portable Contract|Portable Contract]], [[wiki/Shared Fixtures|Shared Fixtures]], [[wiki/Cross-Runtime Capability Parity|Cross-Runtime Capability Parity]] --- ## Definition **Conformance testing verifies that an implementation satisfies a shared behavioral contract rather than merely passing its own local tests.** Every runtime consumes the same fixtures and must agree on accepted inputs, normalized results, and error behavior. ## Project Context The modern X library requires JavaScript, PHP, Python, and Perl runners that execute canonical fixtures directly. A new port is not declared complete because its function names exist; it earns parity by producing the contract's expected observations. ## Key Insight **Conformance converts portability from an architectural intention into a repeatable measurement.** ## See Also [[wiki/Shared Fixtures|Shared Fixtures]], [[wiki/Canonical Capability Name|Canonical Capability Name]], [[wiki/Error Behavior|Error Behavior]], [[wiki/Technical Terms|Technical Terms]]