JSON Schema Compliance

xschema adapters are tested against the official JSON Schema Test Suite, ensuring reliable schema conversion across all supported validation libraries.

What is the JSON Schema Test Suite?

The JSON Schema Test Suite is the official test collection maintained by the JSON Schema organization. It's the industry standard for verifying correct implementation of the JSON Schema specification across all drafts.

Each test case provides:

• A JSON Schema definition
• Sample data to validate against the schema
• Expected validation results (valid or invalid)

The suite covers every keyword and edge case in the specification, from simple type checks to complex recursive references.

How xschema tests compliance

xschema runs compliance tests by:

1. Converting each JSON Schema to native validation code (Zod, ArkType, Effect, Valibot)
2. Executing the generated validator against every test case
3. Comparing actual results to expected outcomes
4. Reporting pass/fail statistics per keyword and draft

Tests run across all supported drafts: draft-03, draft-04, draft-06, draft-07, draft-2019-09, and draft-2020-12.

Static generation approach

Unlike runtime validators that interpret schemas on-the-fly, xschema generates static validation code at build time. This approach offers:

• Type safety: Full TypeScript type inference from schemas
• Performance: No schema parsing at runtime
• Bundle size: Only include the validation code you need
• Predictability: The same schema always generates the same code

However, static generation cannot support certain dynamic JSON Schema features that require runtime evaluation. See Unsupported Features for these limitations.

How coverage is calculated

Coverage percentages reflect real-world usability by excluding tests for features that are fundamentally incompatible with static code generation:

Coverage = Passed / (Total - Unsupported) * 100

Unsupported features are JSON Schema keywords that require runtime scope tracking:

• $dynamicRef / $dynamicAnchor - dynamic reference resolution
• $recursiveRef / $recursiveAnchor - recursive reference resolution
• unevaluatedProperties / unevaluatedItems with applicators - annotation tracking

These features are excluded because no static code generator can implement them - they require a runtime interpreter by design. A 100% coverage score means the adapter handles every test case that can possibly be supported through static code generation.

Understanding results

Each adapter's compliance report shows:

A coverage of 98%+ means the adapter handles nearly all practical JSON Schema use cases correctly.

Learn more