Fix: Allow definitions/properties named 'enum' or 'const' during ref expansion

src/JsonSchema/SchemaStorage.php

@@ -1,4 +1,4 @@
 <?php
 
 declare(strict_types=1);
 
@@ -14,6 +14,41 @@
 {
     public const INTERNAL_PROVIDED_SCHEMA_URI = 'internal://provided-schema/';
 
+    /**
+     * JSON Schema keywords that indicate an object is a schema with validation rules,
+     * not a pure container (like the value of definitions or properties keywords).
+     * 
+     * Note: 'properties' is a schema keyword (e.g., {"type": "object", "properties": {...}}).
+     * The properties *container* (the value) won't have these keywords, so it won't match.
+     * 
+     * Note: 'enum' and 'const' are intentionally excluded as they are handled specially.
+     */
+    private const SCHEMA_KEYWORDS = [
+        // Core schema identifiers
+        '$schema', 'id', '$id', '$comment', 'title', 'description',
+
+        // Type and structure
+        'type', 'properties', 'patternProperties', 'additionalProperties',
+        'items', 'additionalItems', 'required', 'dependencies',
+        'definitions', '$defs',
+
+        // Validation keywords
+        'format', 'pattern',
+        'minimum', 'maximum', 'exclusiveMinimum', 'exclusiveMaximum', 'multipleOf',
+        'minLength', 'maxLength',
+        'minItems', 'maxItems', 'uniqueItems', 'contains',
+        'minProperties', 'maxProperties',
+
+        // Composition
+        'allOf', 'anyOf', 'oneOf', 'not',
+
+        // Conditionals
+        'if', 'then', 'else',
+
+        // Metadata and annotations
+        'default', 'examples', 'readOnly', 'writeOnly'
+    ];
+
     protected $uriRetriever;
     protected $uriResolver;
     protected $schemas = [];
@@ -101,7 +136,9 @@
         }
 
         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;
             }
@@ -205,7 +242,8 @@
             $potentialSubSchemaId = $this->findSchemaIdInObject($potentialSubSchema);
             if (is_string($potentialSubSchemaId) && property_exists($potentialSubSchema, 'type')) {
                 // Enum and const don't allow id as a keyword, see https://github.com/json-schema-org/JSON-Schema-Test-Suite/pull/471
-                if (in_array($propertyName, ['enum', 'const'])) {
+                // Only skip if we're in an actual schema context, not when 'enum'/'const' is a property/definition name
+                if (in_array($propertyName, ['enum', 'const']) && $this->isSchemaObject($schema)) {
                     continue;
                 }
 
@@ -233,4 +271,19 @@
 
         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
+    {
+        foreach (self::SCHEMA_KEYWORDS as $keyword) {
+            if (property_exists($schema, $keyword)) {
+                return true;
+            }
+        }
+
+        return false;
+    }
 }

tests/SchemaStorageTest.php

@@ -305,4 +305,46 @@ public function testNoDoubleResolve(): void
             $schemas['test/schema']->{'$ref'}
         );
     }
+
+    /**
+     * Test that definitions named 'enum' or 'const' are properly resolved
+     * Regression test for UnresolvableJsonPointerException when definitions are named 'enum' or 'const'
+     * Related to: https://github.com/mxr576/oas-validation-issue-on-v6
+     */
+    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'}
+        );
+    }
 }