Add missing imports

graphene/types/tests/test_enum.py

@@ -1,12 +1,15 @@
 from textwrap import dedent
 
 from graphene.compat.middleware import enum_value_convertor_middleware
+
 from ..argument import Argument
 from ..enum import Enum, PyEnum
 from ..field import Field
 from ..inputfield import InputField
-from ..schema import ObjectType, Schema
+from ..inputobjecttype import InputObjectType
 from ..mutation import Mutation
+from ..scalars import String
+from ..schema import ObjectType, Schema
 
 
 def test_enum_construction():