Ignore Introspection queries in QueryComplexity rule (#1788)

Fixes #1204

Author: ruudk

src/Validator/Rules/QueryComplexity.php

@@ -18,6 +18,7 @@
 use GraphQL\Language\VisitorOperation;
 use GraphQL\Type\Definition\Directive;
 use GraphQL\Type\Definition\FieldDefinition;
+use GraphQL\Type\Introspection;
 use GraphQL\Validator\QueryValidationContext;
 
 /**
@@ -117,6 +118,11 @@ protected function nodeComplexity(SelectionNode $node): int
     {
         switch (true) {
             case $node instanceof FieldNode:
+                // Exclude __schema field and all nested content from complexity calculation
+                if ($node->name->value === Introspection::SCHEMA_FIELD_NAME) {
+                    return 0;
+                }
+
                 if ($this->directiveExcludesField($node)) {
                     return 0;
                 }

tests/Validator/QueryComplexityTest.php

@@ -5,6 +5,7 @@
 use GraphQL\Error\Error;
 use GraphQL\Language\AST\NodeKind;
 use GraphQL\Language\Parser;
+use GraphQL\Type\Introspection;
 use GraphQL\Validator\DocumentValidator;
 use GraphQL\Validator\Rules\CustomValidationRule;
 use GraphQL\Validator\Rules\QueryComplexity;
@@ -164,7 +165,16 @@ public function testQueryWithCustomAndSkipDirective(): void
 
     public function testComplexityIntrospectionQuery(): void
     {
-        $this->assertIntrospectionQuery(187);
+        $query = Introspection::getIntrospectionQuery();
+
+        $this->assertDocumentValidator($query, 0);
+    }
+
+    public function testMixedIntrospectionAndRegularFields(): void
+    {
+        $query = 'query MyQuery { __schema { queryType { name } } human { firstName } }';
+
+        $this->assertDocumentValidators($query, 2, 3);
     }
 
     public function testIntrospectionTypeMetaFieldQuery(): void