Fix known type names validation for fragments with experimental variables

CHANGELOG.md

@@ -9,6 +9,10 @@ You can find and compare releases at the [GitHub release page](https://github.co
 
 ## Unreleased
 
+### Fixed
+
+- KnownTypeNames validation for fragments with variables (experimentalFragmentVariables option)
+
 ## v15.20.0
 
 ### Added

src/Language/AST/FragmentDefinitionNode.php

@@ -2,7 +2,7 @@
 
 namespace GraphQL\Language\AST;
 
-class FragmentDefinitionNode extends Node implements ExecutableDefinitionNode, HasSelectionSet
+class FragmentDefinitionNode extends Node implements ExecutableDefinitionNode, HasSelectionSet, TypeSystemDefinitionNode
 {
     public string $kind = NodeKind::FRAGMENT_DEFINITION;
 

tests/Validator/KnownTypeNamesTest.php

@@ -32,6 +32,30 @@ public function testKnownTypeNamesAreValid(): void
         );
     }
 
+    /** @see it('known type names are valid') */
+    public function testKnownTypeWithExperimentalFragmentVariablesAreValid(): void
+    {
+        $this->expectPassesRule(
+            new KnownTypeNames(),
+            '
+      query Foo(
+        $var: String
+        $required: [Int!]!
+        $introspectionType: __EnumValue
+      ) {
+        user(id: 4) {
+          pets { ... on Dog { isAtLocationField(x: 0, y: 0) } }
+        }
+      }
+
+      fragment isAtLocationField($x: Int = 0, $y: Int = 0) on Dog {
+        isAtLocation(x: $x, y: $y)
+      }
+            ',
+            ['experimentalFragmentVariables' => true]
+        );
+    }
+
     /** @see it('unknown type names are invalid') */
     public function testUnknownTypeNamesAreInvalid(): void
     {