Added breaking test to demonstrate wanted subclassing feature.

graphene/relay/tests/test_node.py

@@ -7,6 +7,19 @@ from ..connection import Connection
 from ..node import Node
 
 
+class SharedNodeFields(ObjectType):
+
+    class Meta:
+        interfaces = (Node, )
+
+    shared = String()
+    something_else = String()
+
+    @classmethod
+    def get_node(cls, id, *_):
+        return cls(shared=str(id))
+
+
 class MyNode(ObjectType):
 
     class Meta:
@@ -18,11 +31,18 @@ class MyNode(ObjectType):
         return MyNode(name=str(id))
 
 
+class MyOtherNode(SharedNodeFields):
+    extra_field = String()
+
+    def resolve_extra_field(self, *_):
+        return 'extra field info.'
+
+
 class RootQuery(ObjectType):
     first = String()
     node = Node.Field()
 
-schema = Schema(query=RootQuery, types=[MyNode])
+schema = Schema(query=RootQuery, types=[MyNode, MyOtherNode])
 
 
 def test_node_no_get_node():
@@ -66,6 +86,14 @@ def test_node_query():
     assert executed.data == {'node': {'name': '1'}}
 
 
+def test_subclassed_node_query():
+    executed = schema.execute(
+        '{ node(id:"%s") { ... on MyOtherNode { shared, extraField } } }' % to_global_id("MyOtherNode", 1)
+    )
+    assert not executed.errors
+    assert executed.data == {'node': {'shared': '1', 'extraField': 'extra field info'}}
+
+
 def test_node_query_incorrect_id():
     executed = schema.execute(
         '{ node(id:"%s") { ... on MyNode { name } } }' % "something:2"
@@ -85,6 +113,12 @@ type MyNode implements Node {
   name: String
 }
 
+type MyOtherNode implements Node {
+  shared: String
+  somethingElse: String
+  extraField: String
+}
+
 interface Node {
   id: ID!
 }