Add support for __typename field in QueryPlan (#831)

Author: simPod

src/Type/Definition/QueryPlan.php

@@ -11,6 +11,7 @@
 use GraphQL\Language\AST\FragmentSpreadNode;
 use GraphQL\Language\AST\InlineFragmentNode;
 use GraphQL\Language\AST\SelectionSetNode;
+use GraphQL\Type\Introspection;
 use GraphQL\Type\Schema;
 
 use function array_diff_key;
@@ -168,7 +169,12 @@ private function analyzeSelectionSet(SelectionSetNode $selectionSet, Type $paren
         $implementors = [];
         foreach ($selectionSet->selections as $selectionNode) {
             if ($selectionNode instanceof FieldNode) {
-                $fieldName     = $selectionNode->name->value;
+                $fieldName = $selectionNode->name->value;
+
+                if ($fieldName === Introspection::TYPE_NAME_FIELD_NAME) {
+                    continue;
+                }
+
                 $type          = $parentType->getField($fieldName);
                 $selectionType = $type->getType();
 

tests/Type/QueryPlanTest.php

@@ -72,6 +72,7 @@ public function testQueryPlan(): void
         $doc               = '
       query Test {
         article {
+            __typename
             author {
                 name
                 pic(width: 100, height: 200) {