[
  {
    "description": "validation of null and format",
    "schema": {"type": ["null", "string"], "format": "date-time"},
    "tests": [
      {
        "description": "a valid date-time string",
        "data": "1963-06-19T08:30:06.283185Z",
        "valid": true
      },
      {
        "description": "allow null",
        "data": null,
        "valid": true
      }
    ]
  }
]