Add support for validating $ref siblings in OpenAPI 3.1

[predic8]

Summary by CodeRabbit

• Bug Fixes

  • Improved OpenAPI schema validation for $ref usage.
  • OpenAPI 3.1 now validates keywords alongside referenced schemas.
  • OpenAPI 3.0 continues ignoring sibling keywords next to $ref.
  • Prevented errors when required properties are absent alongside a reference.
  • Improved recursive reference handling and duplicate error prevention.

• Tests

  • Added coverage for $ref siblings, nullability, types, required properties, read-only fields, and recursive schemas across OpenAPI 3.0 and 3.1.

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📥 Commits

Reviewing files that changed from the base of the PR and between ef7aa0a and c276f25.

📒 Files selected for processing (5)

• core/src/main/java/com/predic8/membrane/core/openapi/validators/SchemaValidator.java
• core/src/main/java/com/predic8/membrane/core/openapi/validators/ValidationContext.java
• core/src/test/java/com/predic8/membrane/core/openapi/validators/CompositionTest.java
• core/src/test/java/com/predic8/membrane/core/openapi/validators/RefSiblingsOAS31Test.java
• core/src/test/resources/openapi/specs/composition.yml

🚧 Files skipped from review as they are similar to previous changes (1)

• core/src/main/java/com/predic8/membrane/core/openapi/validators/SchemaValidator.java

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📝 Walkthrough

Walkthrough

The validator now applies OpenAPI-specific $ref sibling rules, handles recursive references by value location, and passes the active schema through validation. Tests cover OAS 3.0 and OAS 3.1 behavior. Object property flag checks handle missing schemas safely.

Changes

$ref sibling validation

Layer / File(s)	Summary
Version-aware $ref processing core/src/main/java/com/predic8/membrane/core/openapi/validators/SchemaValidator.java, core/src/main/java/com/predic8/membrane/core/openapi/validators/ValidationContext.java	OAS 3.1 validates $ref siblings. OAS 3.0 ignores them. Recursive references are limited by schema and JSON pointer. Schema-dependent validation receives the active schema.
Safe property flag lookup core/src/main/java/com/predic8/membrane/core/openapi/validators/ObjectValidator.java	readOnly and writeOnly checks return false when the property schema is absent.
Version-specific regression coverage core/src/test/java/com/predic8/membrane/core/openapi/validators/*, core/src/test/resources/openapi/specs/*	Tests and fixtures cover OAS 3.0 sibling ignoring, OAS 3.1 sibling application, type narrowing, required properties, sibling detection, and recursive validation at nested locations.

Estimated code review effort: 4 (Complex) | ~45 minutes

Merge Risk: 🟡 Moderate · up to c276f

The change applies OpenAPI 3.1 $ref sibling rules and validates recursive values at each nesting level. Deep recursive payloads still need a boundary regression test to confirm they return a controlled validation error rather than exhausting the validation stack.

Sequence Diagram(s)

sequenceDiagram
  participant Request
  participant SchemaValidator
  participant ValidationContext
  participant ReferencedSchema
  Request->>SchemaValidator: validate referring schema
  SchemaValidator->>ValidationContext: track schema and JSON pointer
  SchemaValidator->>SchemaValidator: inspect version-specific `$ref` siblings
  SchemaValidator->>ReferencedSchema: resolve and validate referenced schema
  ReferencedSchema-->>SchemaValidator: return validation errors
  SchemaValidator-->>Request: return validation result

Loading

Poem

A rabbit checks each schema bright
$ref siblings follow OAS rules right
Nested nodes receive their turn
Missing fields make errors return
Empty property maps cause no fright

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 31.67% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 60 functions across 7 files. (1 skipped: …	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely describes the primary change: validating $ref sibling keywords in OpenAPI 3.1.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

Full details: Docstring Coverage

Explanation

Docstring coverage is 31.67% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 60 functions across 7 files. (1 skipped: 1 unsupported.)

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✨ Finishing Touches 💡 1

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• Commit unit tests in branch fix/ref-siblings-fixes-3188

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Actionable comments posted: 1

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Inline comments:
In
`@core/src/main/java/com/predic8/membrane/core/openapi/validators/SchemaValidator.java`:
- Around line 117-118: Update the cycle handling around ctx.hasVisited(name) in
SchemaValidator so recursive references are still validated at new instance
locations; only terminate genuinely non-progressing schema cycles. Track the
reference with its instance path or equivalent context, and add an assertion
covering a nested Node.next object missing the required id property.

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ℹ️ Review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Team

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📥 Commits

Reviewing files that changed from the base of the PR and between cfe7c76 and ef7aa0a.

📒 Files selected for processing (7)

• core/src/main/java/com/predic8/membrane/core/openapi/validators/ObjectValidator.java
• core/src/main/java/com/predic8/membrane/core/openapi/validators/SchemaValidator.java
• core/src/test/java/com/predic8/membrane/core/openapi/validators/RefSiblingsOAS30Test.java
• core/src/test/java/com/predic8/membrane/core/openapi/validators/RefSiblingsOAS31Test.java
• core/src/test/java/com/predic8/membrane/core/openapi/validators/SchemaValidatorTest.java
• core/src/test/resources/openapi/specs/oas31/ref-siblings.yaml
• core/src/test/resources/openapi/specs/ref-siblings.yaml

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