Duplicate fields in deep inputs not validated properly

Replicates graphql/graphql-js@a001adb

Author: Cito

README.md

@@ -13,7 +13,7 @@ a query language for APIs created by Facebook.
 [![Code Style](https://img.shields.io/badge/code%20style-black-000000.svg)](https://github.com/ambv/black)
 
 The current version 1.0.2 of GraphQL-core-next is up-to-date with GraphQL.js version
-14.1.1. All parts of the API are covered by an extensive test suite of currently 1730
+14.1.1. All parts of the API are covered by an extensive test suite of currently 1731
 unit tests.
 
 

graphql/validation/rules/unique_input_field_names.py

@@ -25,7 +25,7 @@ def __init__(self, context: ASTValidationContext) -> None:
 
     def enter_object_value(self, *_args):
         self.known_names_stack.append(self.known_names)
-        self.known_names.clear()
+        self.known_names = {}
 
     def leave_object_value(self, *_args):
         self.known_names = self.known_names_stack.pop()
@@ -42,4 +42,3 @@ def enter_object_field(self, node: ObjectFieldNode, *_args):
             )
         else:
             known_names[field_name] = node.name
-        return False

tests/validation/test_unique_input_field_names.py

@@ -83,3 +83,13 @@ def many_duplicate_input_object_fields():
             """,
             [duplicate_field("f1", 3, 28, 3, 41), duplicate_field("f1", 3, 28, 3, 54)],
         )
+
+    def nested_duplicate_input_object_fields():
+        assert_errors(
+            """
+            {
+              field(arg: { f1: {f2: "value", f2: "value" }})
+            }
+            """,
+            [duplicate_field("f2", 3, 33, 3, 46)],
+        )