fix: prevent $ref property names from corrupting YAML output

[musa-cf]

Problem

When a YAML schema contains a property literally named $ref (e.g. the SCIM Group member $ref field per RFC 7643), openapi-format silently produces {} as output (exit 0, no error on stderr).

This is a data-loss bug: the entire OpenAPI document is replaced with an empty object.

Reproducer

openapi: 3.0.3
info:
  title: SCIM API
  version: 1.0.0
paths: {}
components:
  schemas:
    member:
      type: object
      properties:
        value:
          type: string
        "$ref":
          type: string
          format: uri
          description: The URI of the member resource.

openapi-format input.yaml --output output.yaml
cat output.yaml
# => {}

Root cause

addQuotesToRefInString uses the regex /(\$ref:\s*)([^"'\s>]+)/g. The \s* includes \n, so when $ref: is a YAML mapping key (property name) with its value on the next line, the regex reaches across the newline and wraps the following line's key in quotes:

# Before addQuotesToRefInString:
              $ref:
                description: The URI of the member resource.

# After addQuotesToRefInString:
              $ref:
                'description:' The URI of the member resource.

This produces invalid YAML. In >=1.33.6, the new doc.errors.length > 0 check in parseString returns a SyntaxError object instead of the parsed document. The caller treats this error object as the formatted output, which serializes to {}.

The bug was latent since addQuotesToRefInString was introduced but became fatal in 1.33.6 when the error check was added.

Fix

Replace \s* with [ \t]* in the regex so it only matches horizontal whitespace and stays on the same line. When $ref is a property name, its value is a block mapping on the next line, so the regex correctly skips it. When $ref is a JSON Reference, the value is on the same line and still gets quoted as intended.

Tests added

• Integration test (test/yaml-dollar-ref-property-name/): full input/output fixture with a SCIM-style schema containing a $ref property name
• Unit test (test/util-file.test.js): addQuotesToRefInString should not modify $ref used as a YAML property name
• Unit test (test/util-file.test.js): parseString should parse YAML with $ref as a property name without error

All 509 existing tests continue to pass.

[thim81]

Hi @musa-cf

Thanks for taking the time to create this PR. The PR overall looks in great shape, with a logical improvement and test coverage to showcase the result.

I m going to do one more extended investigation, since there might be a case with " or ' that might bypass the regex.

[musa-cf]

Thank you!