Check anyOf and oneOf schemas in nullable validation

[arttuperala]

test_is_nullable() is executed before the normal test_schema_section() processing, including the anyOf and oneOf checking, takes place, and if your nullable definition comes from inside either anyOf or oneOf, the validation will fail.

[codecov]

Codecov Report

Merging #300 (7eb51c0) into master (b2aa34e) will increase coverage by 0.0%.
The diff coverage is 100.0%.

@@          Coverage Diff           @@
##           master    #300   +/-   ##
======================================
  Coverage    98.6%   98.6%           
======================================
  Files           9       9           
  Lines         522     528    +6     
  Branches       93      97    +4     
======================================
+ Hits          515     521    +6     
  Misses          4       4           
  Partials        3       3           

Impacted Files	Coverage Δ
openapi_tester/schema_tester.py	99.3% <100.0%> (+<0.1%)	⬆️

[sondrelg]

Changes look good to me. Have to admit, it's been a while since I looked at this code, so it's hard to evaluate the PR. Could you elaborate a little, and/or give an example, on what would fail previously that now passes?

[arttuperala]

It basically just allows the test_is_nullable() to pass without issues if the nullable: true comes from within an anyOf or oneOf.

We're basically working with a JSON:API schema that looks a bit something like this:

components:
  schemas:
    reltoone:
      type: object
      properties:
        data:
          $ref: '#/components/schemas/relationshipToOne'
    relationshipToOne:
      anyOf:
      - $ref: '#/components/schemas/nulltype'
      - $ref: '#/components/schemas/linkage'
    nulltype:
      type: object
      nullable: true
      default: null
    linkage:
      type: object
      properties:
        type:
          $ref: '#/components/schemas/type'
        id:
          $ref: '#/components/schemas/id'
        meta:
          $ref: '#/components/schemas/meta'
    ABC:
      type: object
      properties:
        relationships:
          type: object
          properties:
            xyz:
              $ref: '#/components/schemas/reltoone'

And then we'd feed the validator a response like this:

{
    "data": {
        "relationships": {
            "xyz": {
                "data": null
            }
        }
    }
}

Even though /data/relationships/xyz/data is a relationshipToOne, where one of its possible schemas is nulltype with nullable: true, it'd fail the validation because the current code could not peek inside the anyOf array to figure out if one of the possible values is nullable.

[sondrelg]

Looks good to me! I'll release a fix shortly 👍

[arttuperala]

I might have another PR coming up also, since there's also another issue that I'm having with the validators.

[sondrelg]

Ah sorry, missed this. No worries though, I can do another release 👍