Added partial support to Dynamic type (#725)

Author: nikordaris

graphene/types/dynamic.py

@@ -1,4 +1,5 @@
 import inspect
+from functools import partial
 
 from .mountedtype import MountedType
 
@@ -11,7 +12,7 @@ class Dynamic(MountedType):
 
     def __init__(self, type, with_schema=False, _creation_counter=None):
         super(Dynamic, self).__init__(_creation_counter=_creation_counter)
-        assert inspect.isfunction(type)
+        assert inspect.isfunction(type) or isinstance(type, partial)
         self.type = type
         self.with_schema = with_schema
 

graphene/types/tests/test_dynamic.py

@@ -1,3 +1,4 @@
+from functools import partial
 from ..dynamic import Dynamic
 from ..scalars import String
 from ..structures import List, NonNull
@@ -25,3 +26,11 @@ def test_list_non_null():
     dynamic = Dynamic(lambda: List(NonNull(String)))
     assert dynamic.get_type().of_type.of_type == String
     assert str(dynamic.get_type()) == '[String!]'
+
+
+def test_partial():
+    def __type(_type):
+        return _type
+    dynamic = Dynamic(partial(__type, String))
+    assert dynamic.get_type() == String
+    assert str(dynamic.get_type()) == 'String'