Allow adding GraphQL types to Graphene schema

graphene/types/schema.py

@@ -23,6 +23,7 @@ from graphql import (
     GraphQLObjectType,
     GraphQLSchema,
     GraphQLString,
+    GraphQLType,
     Undefined,
 )
 
@@ -106,6 +107,11 @@ class TypeMap(dict):
     def add_type(self, graphene_type):
         if inspect.isfunction(graphene_type):
             graphene_type = graphene_type()
+
+        # If type is a GraphQLType from graphql-core then return it immediately
+        if isinstance(graphene_type, GraphQLType):
+            return graphene_type
+
         if isinstance(graphene_type, List):
             return GraphQLList(self.add_type(graphene_type.of_type))
         if isinstance(graphene_type, NonNull):

graphene/types/tests/test_type_map.py

@@ -1,3 +1,5 @@
+from textwrap import dedent
+
 from graphql.type import (
     GraphQLArgument,
     GraphQLEnumType,
@@ -270,3 +272,44 @@ def test_objecttype_with_possible_types():
     assert graphql_type.is_type_of
     assert graphql_type.is_type_of({}, None) is True
     assert graphql_type.is_type_of(MyObjectType(), None) is False
+
+
+def test_graphql_type():
+    """Type map should allow direct GraphQL types"""
+    MyGraphQLType = GraphQLObjectType(
+        name="MyGraphQLType",
+        fields={
+            "hello": GraphQLField(GraphQLString, resolve=lambda obj, info: "world")
+        },
+    )
+
+    class Query(ObjectType):
+        graphql_type = Field(MyGraphQLType)
+
+        def resolve_graphql_type(root, info):
+            return {}
+
+    schema = Schema(query=Query)
+    assert str(schema) == dedent(
+        """\
+        type Query {
+          graphqlType: MyGraphQLType
+        }
+
+        type MyGraphQLType {
+          hello: String
+        }
+    """
+    )
+
+    results = schema.execute(
+        """
+        query {
+            graphqlType {
+                hello
+            }
+        }
+    """
+    )
+    assert not results.errors
+    assert results.data == {"graphqlType": {"hello": "world"}}