Investigate oneOf usage in API tests

[jeluard]

JSON Schema oneOf usage in API tests is problematic and lead to some workaround:

• lodestar/packages/api/test/utils/checkAgainstSpec.ts

  Line 58 in 4658348

  // For some reason AJV invalidates valid blocks if multiple forks are defined with oneOf

• lodestar/packages/api/test/utils/checkAgainstSpec.ts

  Line 82 in 4658348

  // For some reason AJV invalidates valid blocks if multiple forks are defined with oneOf

• lodestar/packages/api/test/utils/parseOpenApiSpec.ts

  Line 145 in 4658348

  // Pick single oneOf, AJV has trouble validating against blocks and states

Investigate the underlying cause as it might lead to false negative or ignored failures.

[jeluard]

Note that the OpenAPI description of the beacon-APIs is not valid (see ethereum/beacon-APIs#393). Reported errors looks related to this issue:

{
    "schemaValidationMessages": [
        {
            "level": "error",
            "domain": "validation",
            "keyword": "oneOf",
            "message": "instance failed to match exactly one schema (matched 0 out of 2)",
            "schema": {
                "loadingURI": "#",
                "pointer": "/definitions/Components/properties/schemas/patternProperties/^[a-zA-Z0-9\\.\\-_]+$"
            },
            "instance": {
                "pointer": "/components/schemas/Bellatrix.BeaconBlock"
            }
        },
        {
            "level": "error",
            "domain": "validation",
            "keyword": "oneOf",
            "message": "instance failed to match exactly one schema (matched 0 out of 2)",
            "schema": {
                "loadingURI": "#",
                "pointer": "/definitions/Components/properties/schemas/patternProperties/^[a-zA-Z0-9\\.\\-_]+$"
            },
            "instance": {
                "pointer": "/components/schemas/Bellatrix.SignedBeaconBlock"
            }
        },
        {
            "level": "error",
            "domain": "validation",
            "keyword": "oneOf",
            "message": "instance failed to match exactly one schema (matched 0 out of 2)",
            "schema": {
                "loadingURI": "#",
                "pointer": "/definitions/Components/properties/schemas/patternProperties/^[a-zA-Z0-9\\.\\-_]+$"
            },
            "instance": {
                "pointer": "/components/schemas/Blob"
            }
        },
        {
            "level": "error",
            "domain": "validation",
            "keyword": "oneOf",
            "message": "instance failed to match exactly one schema (matched 0 out of 2)",
            "schema": {
                "loadingURI": "#",
                "pointer": "/definitions/Components/properties/schemas/patternProperties/^[a-zA-Z0-9\\.\\-_]+$"
            },
            "instance": {
                "pointer": "/components/schemas/Capella.BeaconBlock"
            }
        },
        {
            "level": "error",
            "domain": "validation",
            "keyword": "oneOf",
            "message": "instance failed to match exactly one schema (matched 0 out of 2)",
            "schema": {
                "loadingURI": "#",
                "pointer": "/definitions/Components/properties/schemas/patternProperties/^[a-zA-Z0-9\\.\\-_]+$"
            },
            "instance": {
                "pointer": "/components/schemas/Capella.SignedBeaconBlock"
            }
        },
        {
            "level": "error",
            "domain": "validation",
            "keyword": "oneOf",
            "message": "instance failed to match exactly one schema (matched 0 out of 2)",
            "schema": {
                "loadingURI": "#",
                "pointer": "/definitions/Components/properties/schemas/patternProperties/^[a-zA-Z0-9\\.\\-_]+$"
            },
            "instance": {
                "pointer": "/components/schemas/Deneb.BeaconBlock"
            }
        },
        {
            "level": "error",
            "domain": "validation",
            "keyword": "oneOf",
            "message": "instance failed to match exactly one schema (matched 0 out of 2)",
            "schema": {
                "loadingURI": "#",
                "pointer": "/definitions/Components/properties/schemas/patternProperties/^[a-zA-Z0-9\\.\\-_]+$"
            },
            "instance": {
                "pointer": "/components/schemas/Deneb.BlobSidecars"
            }
        },
        {
            "level": "error",
            "domain": "validation",
            "keyword": "oneOf",
            "message": "instance failed to match exactly one schema (matched 0 out of 2)",
            "schema": {
                "loadingURI": "#",
                "pointer": "/definitions/Components/properties/schemas/patternProperties/^[a-zA-Z0-9\\.\\-_]+$"
            },
            "instance": {
                "pointer": "/components/schemas/Deneb.BlockContents"
            }
        },
        {
            "level": "error",
            "domain": "validation",
            "keyword": "oneOf",
            "message": "instance failed to match exactly one schema (matched 0 out of 2)",
            "schema": {
                "loadingURI": "#",
                "pointer": "/definitions/Components/properties/schemas/patternProperties/^[a-zA-Z0-9\\.\\-_]+$"
            },
            "instance": {
                "pointer": "/components/schemas/Deneb.SignedBeaconBlock"
            }
        },
        {
            "level": "error",
            "domain": "validation",
            "keyword": "oneOf",
            "message": "instance failed to match exactly one schema (matched 0 out of 2)",
            "schema": {
                "loadingURI": "#",
                "pointer": "/definitions/Components/properties/schemas/patternProperties/^[a-zA-Z0-9\\.\\-_]+$"
            },
            "instance": {
                "pointer": "/components/schemas/Deneb.SignedBlobSidecar"
            }
        },
        {
            "level": "error",
            "domain": "validation",
            "keyword": "oneOf",
            "message": "instance failed to match exactly one schema (matched 0 out of 2)",
            "schema": {
                "loadingURI": "#",
                "pointer": "/definitions/Components/properties/schemas/patternProperties/^[a-zA-Z0-9\\.\\-_]+$"
            },
            "instance": {
                "pointer": "/components/schemas/Deneb.SignedBlockContents"
            }
        }
    ]
}