__ is reserved for introspection (#2805)

* fix error as __ is reserved for introspection

graphql "__fake" must not begin with "__", which is reserved by GraphQL introspection.

c.f. graphql/graphql-spec#244

* run yarn changset

Author: saerdnaer

.changeset/gentle-foxes-look.md

@@ -0,0 +1,5 @@
+---
+'@graphql-tools/utils': patch
+---
+
+\_\_ is reserved for introspection

packages/utils/src/stub.ts

@@ -39,7 +39,7 @@ export function createNamedStub(
   return new constructor({
     name,
     fields: {
-      __fake: {
+      _fake: {
         type: GraphQLString,
       },
     },
@@ -67,7 +67,7 @@ export function isNamedStub(type: GraphQLNamedType): boolean {
   if (isObjectType(type) || isInterfaceType(type) || isInputObjectType(type)) {
     const fields = type.getFields();
     const fieldNames = Object.keys(fields);
-    return fieldNames.length === 1 && fields[fieldNames[0]].name === '__fake';
+    return fieldNames.length === 1 && fields[fieldNames[0]].name === '_fake';
   }
 
   return false;