fix: do not read a $ref inside default, const, enum or examples as a reference

index.js

@@ -4,6 +4,10 @@ const { dequal: deepEqual } = require('dequal')
 
 const jsonSchemaRefSymbol = Symbol.for('json-schema-ref')
 
+// the keywords whose value is data, not a schema: a $ref or an $id inside them is a property
+// name of the instance, not a reference
+const dataKeywords = new Set(['default', 'const', 'enum', 'examples'])
+
 class RefResolver {
   #schemas
   #derefSchemas
@@ -50,6 +54,7 @@ class RefResolver {
     }
 
     for (const key in schema) {
+      if (dataKeywords.has(key)) continue
       if (typeof schema[key] === 'object' && schema[key] !== null) {
         this.addSchema(schema[key], rootSchemaId, false)
       }
@@ -202,6 +207,7 @@ class RefResolver {
     }
 
     for (const key in derefSchema) {
+      if (dataKeywords.has(key)) continue
       const value = derefSchema[key]
       if (typeof value === 'object' && value !== null) {
         derefSchema[key] = this.#addDerefSchema(value, rootSchemaId, false, refs)

test/data-keywords.test.js

@@ -0,0 +1,27 @@
+'use strict'
+
+const assert = require('node:assert/strict')
+const { test } = require('node:test')
+const { RefResolver } = require('../index.js')
+
+// a $ref inside default, const, enum or examples is a property of the instance, not a reference,
+// and was collected as one: the dependencies could not be resolved and the deref walked into data
+test('does not read a $ref inside a data keyword as a reference', () => {
+  const refResolver = new RefResolver()
+  const schema = {
+    $id: 'schemaId',
+    type: 'object',
+    properties: {
+      a: { type: 'object', default: { $ref: 'nowhere#/x', $id: 'nowhere' } },
+      b: { const: { $ref: 'nowhere' } },
+      c: { enum: [{ $ref: 'nowhere' }] },
+      d: { type: 'string', examples: [{ $ref: 'nowhere' }] }
+    }
+  }
+  refResolver.addSchema(schema)
+
+  assert.deepStrictEqual(refResolver.getSchemaRefs('schemaId'), [])
+  assert.deepStrictEqual(refResolver.getSchemaDependencies('schemaId'), {})
+  assert.deepStrictEqual(refResolver.getDerefSchema('schemaId'), schema)
+  assert.equal(refResolver.hasSchema('nowhere'), false)
+})