Fix enum/const property name handling in SchemaStorage

Add conditional check to only skip enum/const when they are schema keywords, not property/definition names. This fixes the issue where definitions named 'enum' or 'const' were being skipped during ref expansion.

Co-authored-by: DannyvdSluijs <618940+DannyvdSluijs@users.noreply.github.com>

Author: Copilot

src/JsonSchema/SchemaStorage.php

@@ -101,7 +101,9 @@ private function expandRefs(&$schema, ?string $parentId = null): void
         }
 
         foreach ($schema as $propertyName => &$member) {
-            if (in_array($propertyName, ['enum', 'const'])) {
+            // Only skip enum/const if we're in an actual schema object (has validation keywords),
+            // not in a container object like definitions where 'enum' might be a property/definition name
+            if (in_array($propertyName, ['enum', 'const']) && $this->isSchemaObject($schema)) {
                 // Enum and const don't allow $ref as a keyword, see https://github.com/json-schema-org/JSON-Schema-Test-Suite/pull/445
                 continue;
             }
@@ -233,4 +235,30 @@ private function findSchemaIdInObject(object $schema): ?string
 
         return null;
     }
+
+    /**
+     * Check if an object appears to be a JSON Schema object (with validation keywords)
+     * vs a pure container object (like definitions, properties containers)
+     */
+    private function isSchemaObject(object $schema): bool
+    {
+        // Common JSON Schema keywords that indicate this is a schema, not a container
+        $schemaKeywords = [
+            'type', 'properties', 'items', 'additionalProperties', 'additionalItems',
+            'required', 'allOf', 'anyOf', 'oneOf', 'not', 'format',
+            'minimum', 'maximum', 'exclusiveMinimum', 'exclusiveMaximum',
+            'minLength', 'maxLength', 'pattern', 'minItems', 'maxItems',
+            'uniqueItems', 'minProperties', 'maxProperties', 'multipleOf',
+            '$ref', '$schema', 'id', '$id', 'title', 'description',
+            'default', 'examples', 'patternProperties', 'dependencies'
+        ];
+
+        foreach ($schemaKeywords as $keyword) {
+            if (property_exists($schema, $keyword)) {
+                return true;
+            }
+        }
+
+        return false;
+    }
 }

tests/SchemaStorageTest.php

@@ -305,4 +305,45 @@ public function testNoDoubleResolve(): void
             $schemas['test/schema']->{'$ref'}
         );
     }
+
+    /**
+     * Test that definitions named 'enum' or 'const' are properly resolved
+     * Regression test for: https://github.com/jsonrainbow/json-schema/issues/XXX
+     */
+    public function testDefinitionNamedEnumIsResolved(): void
+    {
+        // Schema with a definition named 'enum' that contains a $ref
+        $schema = (object) [
+            'id' => 'http://example.com/schema.json',
+            'definitions' => (object) [
+                'enum' => (object) [
+                    '$ref' => 'http://json-schema.org/draft-04/schema#/properties/enum'
+                ],
+                'const' => (object) [
+                    '$ref' => 'http://json-schema.org/draft-04/schema#/properties/const'
+                ]
+            ]
+        ];
+
+        $uriRetriever = $this->prophesize(\JsonSchema\UriRetrieverInterface::class);
+        $uriRetriever->retrieve('http://example.com/schema.json')
+            ->willReturn($schema)
+            ->shouldBeCalled();
+
+        $schemaStorage = new SchemaStorage($uriRetriever->reveal());
+        $schemaStorage->addSchema('http://example.com/schema.json');
+
+        // Verify the refs in the 'enum' and 'const' definitions were expanded
+        $storedSchema = $schemaStorage->getSchema('http://example.com/schema.json');
+        
+        // The $ref should have been expanded to include the full URI
+        $this->assertStringContainsString(
+            'http://json-schema.org/draft-04/schema#',
+            $storedSchema->definitions->enum->{'$ref'}
+        );
+        $this->assertStringContainsString(
+            'http://json-schema.org/draft-04/schema#',
+            $storedSchema->definitions->const->{'$ref'}
+        );
+    }
 }