Stop interpreting x-nullable

src/Parser/Schema/Reader.php

@@ -32,7 +32,7 @@
     private const array PARAMETER_FIELDS = [
         'type', 'format', 'items', 'default', 'enum', 'maximum', 'exclusiveMaximum',
         'minimum', 'exclusiveMinimum', 'maxLength', 'minLength', 'pattern',
-        'maxItems', 'minItems', 'uniqueItems', 'multipleOf', 'description', 'x-nullable',
+        'maxItems', 'minItems', 'uniqueItems', 'multipleOf', 'description',
     ];
 
     public function __construct(private Dialect $dialect) {}
@@ -161,7 +161,7 @@ private function common(array $data): array
         return [
             'title' => Value::optionalString($data, 'title'),
             'description' => Value::optionalString($data, 'description') ?? '',
-            'nullable' => (bool) ($data['nullable'] ?? $data['x-nullable'] ?? false),
+            'nullable' => (bool) ($data['nullable'] ?? false),
             'default' => $data['default'] ?? null,
             'enum' => $enum,
             'format' => Value::optionalString($data, 'format'),

tests/CrossVersionFixtureTest.php

@@ -105,7 +105,7 @@ public function test_equivalent_documents_produce_equivalent_canonical_behavior(
         self::assertSame('int64', $pet->properties['id']->format);
         self::assertInstanceOf(StringSchema::class, $pet->properties['name']);
         self::assertSame(1, $pet->properties['name']->minLength);
-        self::assertTrue($pet->properties['nickname']->nullable);
+        self::assertFalse($pet->properties['nickname']->nullable);
         self::assertInstanceOf(ReferenceSchema::class, $pet->properties['parent']);
         self::assertSame($this->petReference($version), $pet->properties['parent']->reference);
         self::assertSame(['available', 'adopted'], $pet->properties['status']->enum);

tests/Fixtures/openapi-2.0.json

@@ -132,8 +132,7 @@
           "minLength": 1
         },
         "nickname": {
-          "type": "string",
-          "x-nullable": true
+          "type": "string"
         },
         "parent": {
           "$ref": "#/definitions/Pet"

tests/Fixtures/openapi-3.0.json

@@ -148,8 +148,7 @@
             "minLength": 1
           },
           "nickname": {
-            "type": "string",
-            "nullable": true
+            "type": "string"
           },
           "parent": {
             "$ref": "#/components/schemas/Pet"

tests/Fixtures/openapi-3.1.json

@@ -148,7 +148,7 @@
             "minLength": 1
           },
           "nickname": {
-            "type": ["string", "null"]
+            "type": "string"
           },
           "parent": {
             "$ref": "#/components/schemas/Pet"

tests/Schema/ReaderTest.php

@@ -66,13 +66,20 @@ public function test_an_explicit_enum_wins_over_const(): void
         self::assertSame(['a', 'b'], $this->reader(Version::V3_1)->read(['type' => 'string', 'const' => 'c', 'enum' => ['a', 'b']], '#/x')->enum);
     }
 
-    public function test_nullability_is_read_from_either_keyword(): void
+    public function test_nullability_is_read_from_the_nullable_keyword(): void
     {
         self::assertTrue($this->reader(Version::V3_0)->read(['type' => 'string', 'nullable' => true], '#/x')->nullable);
-        self::assertTrue($this->reader(Version::V2)->read(['type' => 'string', 'x-nullable' => true], '#/x')->nullable);
         self::assertFalse($this->reader(Version::V3_0)->read(['type' => 'string'], '#/x')->nullable);
     }
 
+    public function test_x_nullable_remains_an_uninterpreted_extension(): void
+    {
+        $schema = $this->reader(Version::V2)->read(['type' => 'string', 'x-nullable' => true], '#/x');
+
+        self::assertFalse($schema->nullable);
+        self::assertSame(['x-nullable' => true], $schema->extensions);
+    }
+
     public function test_references_are_left_unexpanded_so_recursive_graphs_terminate(): void
     {
         $schema = $this->reader(Version::V3_1)->read(['$ref' => '#/components/schemas/Pet'], '#/x');
@@ -245,8 +252,8 @@ public function test_parameter_fields_are_lifted_into_a_schema_and_non_schema_ke
 
         self::assertInstanceOf(IntegerSchema::class, $schema);
         self::assertSame(1, $schema->minimum);
-        self::assertTrue($schema->nullable);
-        self::assertSame(['x-nullable' => true], $schema->extensions, "'x-nullable' is read as nullability and still kept as an extension");
+        self::assertFalse($schema->nullable);
+        self::assertSame([], $schema->extensions);
     }
 
     public function test_extensions_are_carried_onto_the_schema(): void