Add schema validation for unknown keys in required property

[ariesclark]

{
    "type": "object",
    "required": ["foo", "bar"],
    "properties": {
        "foo": {
            "type": "number"
        }
    }
}

I think the schemasafe strict? validator should throw an error in this case.

[ChALkeR]

Hm. Technically, this is not an error per the JSON Schema spec, and has a reasonable meaning.

Schema like that doesn't make sense if there is an immediate additionalProperties: false there though.

And using strong mode of schemasafe, it will ensure that all properties should be validated.

But they could be validated via more complex rules than the one here, and e.g. doing this is possible even in strong mode:

{
  $schema: 'http://json-schema.org/draft/2020-12/schema#',
  type: 'object',
  required: ['foo', 'bar'],
  properties: {
    foo: {
      type: 'number',
    },
  },
  allOf: [
    {
      required: [],
      properties: {
        bar: {
          type: 'number',
        },
      },
    },
  ],
  unevaluatedProperties: false,
}

Also, a more complex example would be possible with refs.

That said, a validation of required in cases where we can statically prove that those properties are not possible can be done. Just not with this example (as it's missing additionalProperites or unevaluatedProperties).

Sorry for the late reply.

[ChALkeR]

Implemented in 1007440914ba51ba0264c972c2dd455f63642c72.

Not that this check is present only for cases when either additionalProperties: false or a statically-provable unevaluatedProperties: false are used, so we can be sure that required attempts to list a property that is forbidden by either of those.

Upd: old test fixup in 22b16f0dba6fa7cf5400af487c5c1dc9d9b71a22.

[ChALkeR]

This check also works with inherited required, i.e. this schema throws at compile time:

{
  type: 'object',
  required: [],
  properties: {
    foo: {
      type: 'number',
    },
  },
  allOf: [
    {
      required: ['foo', 'bar'],
    },
  ],
  unevaluatedProperties: false,
}

~That said, additionalProperties: false checks only adjacent required for now, so this would pass with additionalProperties instead of unevaluatedProperties.~

~Let's reopen as there is room for improvement.~

Upd: fixed in efd613a.