Bug related to additionalProperties and oneOf

[fabioperrella]

Describe the bug
A clear and concise description of what the bug is.

Spectral is showing the error oas3-valid-oas-content-example in a scenario that I didn't expect

To Reproduce

1. Given this yaml:

openapi: 3.0.0
tags:
  - name: Preview
info:
  version: 1.0.0
  title: lala
  contact:
    name: Team X
    url: 'http://lala.com'
  description: Lala
servers:
  - url: https://lala.com
    description: lala
components:
  schemas:
    Default:
      type: object
      properties:
        url:
          type: string
          nullable: true
    Audio:
      allOf:
        - $ref: '#/components/schemas/Default'
        - type: object
          properties:
            audio_url:
              type: string
              nullable: false

paths:
  '/lala/{id}':
    parameters:
      - schema:
          type: string
        name: id
        in: path
        required: true
        description: lala
    get:
      description: Returns lala
      tags:
        - Preview
      parameters:
        - in: query
          name: id
          description: 'lala'
          schema:
            type: string
          example: 2c0ed7250ea9c8b65c18dfbf4efdff73b9aedf38
      responses:
        '200':
          description: Successful response
          content:
            application/json:
              schema:
                type: object
                properties:
                  previews:
                    type: object
                    additionalProperties:
                      oneOf:
                        - $ref: '#/components/schemas/Default'
                        - $ref: '#/components/schemas/Audio'    
              example:
                previews:
                  abc123aa:
                    url: https://example.com/preview1.jpeg
                  sdja6tsj:
                    url: null
                    audio_url: https://example.com/audio.jpeg
      operationId: lala
      summary: lala

2. Run this CLI command

docker run --rm -v $PWD:/tmp -it stoplight/spectral lint -v -F hint "/tmp/openapi.yaml"

3. See error

67:28  error  oas3-valid-oas-content-example  `abc123aa` property should match exactly one schema in oneOf

Expected behavior

I'm pretty sure I specified the example correctly and it shouldn't return an error

Environment (remove any that are not applicable):

• Library version: stoplight/spectral:latest (0bca0b3aa66a)
• OS: MacOS

[mnaumanali94]

@P0lip Does spectral support objects in additionalProperties?

[anshul-raman]

Hi, I was able to solve this issue by adding a required field in the schema.

[teameh]

Adding all properties as required is indeed a good workaround.

    Shape:
      oneOf:
        - $ref: '#/components/schemas/Rectangle'
        - $ref: '#/components/schemas/Circle'
      discriminator:
        propertyName: shapeType
        mapping:
          rectangle: '#/components/schemas/Rectangle'
          circle: '#/components/schemas/Circle'
      example:
        shapeType: rectangle
        width: 10
        height: 20

    Rectangle:
      type: object
      required: [shapeType, width, height] <-- all required
      properties:
        shapeType:
          type: string
        width:
          type: number
        height:
          type: number

    Circle:
      type: object
      required: [shapeType, radius] <-- all required
      properties:
        shapeType:
          type: string
        radius:
          type: number

However, this should also validate fine:

    Rectangle:
      type: object
      required: [shapeType] <-- only discriminator is required
      properties:
        shapeType:
          type: string
        width:
          type: number
        height:
          type: number

Instead, this yields "0" property must match exactly one schema in oneOf