Test for unevaluatedProperties peering inside an allOf

[gregsdennis]

This question was brought up in the Slack workspace.

(The schema was originally in YAML, but I've translated to JSON for the issue.)

---

Given a schema

{
  "unevaluatedProperties": false,
  "allOf": [
    {
      "properties": {
        "foo": { "type": ["string", "null"] },
        "bar": { "type": ["string", "null"] }
      }
    },
    {
      "additionalProperties": {
        "not": { "enum": [ null ] }
      }
    }
  ]
}

should the instance

{"bar": "foo", "bob": "who?"}

pass validation?

The thing to note here is that additionalProperties, regardless of the subschema that's in it, visits all of the properties of any object instance that's given to it. This means that unevaluatedProperties is effectively a no-op.

The evaluation proceeds as follows:

1. /unevaluatedProperties must be run last, so we save it for later.
2. /allOf/properties/foo isn't found. Pass ✔️
3. /allOf/properties/bar is found, and it's a string. Pass ✔️
4. /additionalProperties evaluates all properties not defined by properties as:
   1. /additionalProperties/not/enum
      1. instance /bar was evaluated by properties skip. Pass ✔️
      2. instance /bob is not null. Pass ✔️
5. Return to /unevaluatedProperties
   1. instance /bar and instance /bob were both evaluated within the allOf so unevaluatedProperties has nothing to do. Pass ✔️

All paths pass validation.

I'll write a test for this and create a PR. Just wanted to get an issue going for it.

[Julian]

Awesome, looks reasonable certainly -- we don't yet have any unevaluatedProperties tests :/ but yeah definitely looks worth adding.

[handrews]

See als #305 #294 and #290

[ssilverman]

Step 4.i.a. certainly passes, but I disagree on the reason. I thought "additionalProperties" only looks at properties in the same schema? In this example, all the properties are defined in a different schema than "additionalProperties". How can instance /bar already have been evaluated? My understanding tells me that it passes only because it's not null.

[Relequestual]

@ssilverman You're correct.

In the provided schema, the additionalProperties subschema is applied to all object values.

It's a tricky one to reason about because not doesn't create an annotations, but the resulting assertion evaluation of additionalProperties DOES create an annotation, and therefore all properties are consider "evaulated [to be valid]".

[handrews]

@ssilverman yeah in this case, there aren't any other properties defined in the same schema object as additionalProperties, so it behaves more like and allProperties keyword would be expected to behave. This is useful for the common case of a generic dictionary type (mapping of string to some other type with no special case properties).