Let default resolver check for Mapping instead of dict (#102)

Author: Cito

src/graphql/execution/execute.py

@@ -1,4 +1,5 @@
 from asyncio import gather
+from collections.abc import Mapping
 from typing import (
     Any,
     Awaitable,
@@ -1116,7 +1117,7 @@ def invalid_return_type_error(
 
 def get_typename(value: Any) -> Optional[str]:
     """Get the ``__typename`` property of the given value."""
-    if isinstance(value, dict):
+    if isinstance(value, Mapping):
         return value.get("__typename")
     # need to de-mangle the attribute assumed to be "private" in Python
     for cls in value.__class__.__mro__:
@@ -1193,7 +1194,7 @@ def default_field_resolver(source: Any, info: GraphQLResolveInfo, **args: Any) -
     field_name = info.field_name
     value = (
         source.get(field_name)
-        if isinstance(source, dict)
+        if isinstance(source, Mapping)
         else getattr(source, field_name, None)
     )
     if callable(value):

tests/execution/test_resolve.py

@@ -1,3 +1,5 @@
+from collections import ChainMap
+
 from graphql import graphql_sync
 from graphql.type import (
     GraphQLArgument,
@@ -25,7 +27,7 @@ class RootValue:
             root_value=RootValue(),
         ) == ({"test": "testValue"}, None,)
 
-    def default_function_accesses_keys():
+    def default_function_accesses_keys_of_dict():
         root_value = {"test": "testValue"}
 
         assert graphql_sync(
@@ -34,6 +36,16 @@ def default_function_accesses_keys():
             root_value=root_value,
         ) == ({"test": "testValue"}, None)
 
+    def default_function_accesses_keys_of_chain_map():
+        # use a mapping that is not a subclass of dict
+        root_value = ChainMap({"test": "testValue"})
+
+        assert graphql_sync(
+            schema=_test_schema(GraphQLField(GraphQLString)),
+            source="{ test }",
+            root_value=root_value,
+        ) == ({"test": "testValue"}, None)
+
     def default_function_calls_methods():
         class RootValue:
             _secret = "secretValue"