Incorrect Detection of Breaking Change for Default Values

[Krzysztof-Kolodziejczyk]

Incorrect Detection of Breaking Change for Default Values in oasdiff

Description

The oasdiff tool is incorrectly marking the addition of a new required property with a default value in request bodies as a breaking change. According to OpenAPI specifications, if a new required field in the request body schema is assigned a default value, it should not be considered a breaking change because it does not require any changes from the client’s side to maintain compatibility.

Versions

• oasdiff Version: 1.10.9
• OpenAPI Specification Files: Version 1.1 and 1.2

Steps to Reproduce

1. OpenAPI Specification File 1.1 (api-1.1.yaml):

   
   openapi: 3.0.0
   info:
    title: Order API
    version: '1.1'
   paths:
    /order:
      post:
        summary: Create a new order
        requestBody:
          required: true
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Order'
        responses:
          '200':
            description: Order created
   components:
    schemas:
      Order:
        type: object
        properties:
          itemId:
            type: string

2. OpenAPI Specification File 1.2 (api-1.2.yaml):

   openapi: 3.0.0
   info:
   title: Order API
   version: '1.2'
   paths:
   /order:
   post:
     summary: Create a new order
     requestBody:
       required: true
       content:
         application/json:
           schema:
             $ref: '#/components/schemas/Order'
     responses:
       '200':
         description: Order created
   components:
   schemas:
   Order:
     type: object
     properties:
       itemId:
         type: string
       quantity:
         type: number
         default: 0
     required:
       - quantity

3. Run oasdiff on these files: Use the following command to compare the two versions of the API specifications:

   oasdiff api-1.1.yaml api-1.2.yaml

4. Output

   
   1 breaking changes: 1 error, 0 warning
   error   [new-required-request-property] at api-1.2.yaml
   in API POST /order
           added the new required request property 'quantity'