Prevent infinite loop on invalid introspection

Replicates graphql/graphql-js@6b033c2

Author: Cito

README.md

@@ -13,7 +13,7 @@ a query language for APIs created by Facebook.
 
 The current version 1.0.0 of GraphQL-core-next is up-to-date with GraphQL.js
 version 14.0.1. All parts of the API are covered by an extensive test suite of
-currently 1604 unit tests.
+currently 1606 unit tests.
 
 
 ## Documentation

graphql/utilities/build_client_schema.py

@@ -1,4 +1,4 @@
-from typing import cast, Callable, Dict, Sequence
+from typing import cast, Callable, Dict, List, Sequence
 
 from ..error import INVALID
 from ..language import DirectiveLocation, parse_value
@@ -126,8 +126,9 @@ def build_object_def(object_introspection: Dict) -> GraphQLObjectType:
         return GraphQLObjectType(
             name=object_introspection['name'],
             description=object_introspection.get('description'),
-            interfaces=[
-                get_interface_type(interface) for interface in interfaces],
+            interfaces=lambda: [
+                get_interface_type(interface)
+                for interface in cast(List[Dict], interfaces)],
             fields=lambda: build_field_def_map(object_introspection))
 
     def build_interface_def(
@@ -146,7 +147,8 @@ def build_union_def(union_introspection: Dict) -> GraphQLUnionType:
         return GraphQLUnionType(
             name=union_introspection['name'],
             description=union_introspection.get('description'),
-            types=[get_object_type(type_) for type_ in possible_types])
+            types=lambda: [get_object_type(type_)
+                           for type_ in cast(List[Dict], possible_types)])
 
     def build_enum_def(enum_introspection: Dict) -> GraphQLEnumType:
         if enum_introspection.get('enumValues') is None:

tests/utilities/test_build_client_schema.py

@@ -448,3 +448,38 @@ def succeeds_on_deep_types_less_or_equal_7_levels():
 
         introspection = introspection_from_schema(schema)
         build_client_schema(introspection)
+
+    def describe_prevents_infinite_recursion_on_invalid_introspection():
+
+        def recursive_interfaces():
+            introspection = {
+                '__schema': {
+                    'types': [{
+                        'name': 'Foo',
+                        'kind': 'OBJECT',
+                        'fields': [],
+                        'interfaces': [{'name': 'Foo'}],
+                    }],
+                },
+            }
+            with raises(TypeError) as exc_info:
+                build_client_schema(introspection)
+            assert str(exc_info.value) == (
+                'Foo interfaces cannot be resolved: '
+                'Expected Foo to be a GraphQL Interface type.')
+
+        def recursive_union():
+            introspection = {
+                '__schema': {
+                    'types': [{
+                        'name': 'Foo',
+                        'kind': 'UNION',
+                        'possibleTypes': [{'name': 'Foo'}],
+                    }],
+                },
+            }
+            with raises(TypeError) as exc_info:
+                build_client_schema(introspection)
+            assert str(exc_info.value) == (
+                'Foo types cannot be resolved: '
+                'Expected Foo to be a GraphQL Object type.')