broken-json-pointer.rb

require 'json'
require 'json-schema'

schema = JSON.parse <<JSON
{
  "$schema": "http://json-schema.org/draft-04/schema#",
  "type": "object",
  "properties": {
    "tag": {
      "oneOf": [
        {
          "$ref": "#/definitions/some:thing"
        },
        {
          "type": "null"
        }
      ]
    }
  },
  "definitions": {
    "some:thing": {
      "type": "object",
      "properties": {
        "id": {
          "type": [
            "number"
          ]
        }
      },
      "required": [
        "id"
      ]
    }
  }
}
JSON

data       = JSON.parse('{"tag": {"id": 1}}')
empty_data = JSON.parse('{}')
nil_data   = JSON.parse('{"tag": null}')

# According to [1] three should be valid but raise:
#
#   .../gems/json-schema-2.6.1/lib/json-schema/attributes/ref.rb:63:
#   in `block in get_referenced_uri_and_schema':
#   The fragment '/definitions/:thing' does not exist on schema
#   2b4d1637-5825-532b-a8a0-2a531331cdad
#   (JSON::Schema::SchemaError)
#
JSON::Validator.validate!(schema, data)
JSON::Validator.validate!(schema, empty_data)
JSON::Validator.validate!(schema, nil_data)

# [1] http://jsonschemalint.com/draft4/ you can just copy paste
# schema and datas from above