github.com/kaptinlin/jsonschema@v0.4.6/testdata/JSON-Schema-Test-Suite/tests/draft2020-12/optional/cross-draft.json

[
    {
        "description": "refs to historic drafts are processed as historic drafts",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "type": "array",
            "$ref": "http://localhost:1234/draft2019-09/ignore-prefixItems.json"
        },
        "tests": [
            {
                "description": "first item not a string is valid",
                "comment": "if the implementation is not processing the $ref as a 2019-09 schema, this test will fail",
                "data": [1, 2, 3],
                "valid": true
            }
        ]
    }
]