Invalid schemas found via hypothesis-jsonschema

[Zac-HD]

Hi there! I've been using the schemastore to provide test inputs for my hypothesis-jsonschema library, which generates valid instances for jsonschemas. In the process, I've bumped into some pretty strange use-cases, and discovered that a few of the schemas here aren't actually valid!

• The Release Drafter configuration file schema contains "required": [] in an object subschema, but an empty list is not valid for this keyword
• The Cirrus CI configuration files and Bamboo Specs schemas contain references to definitions which don't actually exist in the schema
• The TypeScript Lint configuration file contains a reference to an items key which is a list of schemas, and while valid for the items keyword this is an invalid reference target
• and several others have invalid $schema keys, which emit a warning when validated with the Python jsonschema library using jsonschema.validators.validator_for(schema).check_schema(schema) - this might be a useful check to add to CI?

I hope reporting this is helpful - it's not especially detailed information, but I had to add some extra logging code to get this far and don't have any advantage for further debugging or a fix.

[madskristensen]

That's super cool. Currently, we use the tv4 module to test for json schema validity, but it's starting to show its age.

[Zac-HD]

You might also want to try to resolve each reference and check the result is valid; doing that for schemas without any recursive references is how I caught three that otherwise seemed fine :)