Add test for dict assignment of native subclass

Author: msimacek

graalpython/com.oracle.graal.python.test/src/tests/cpyext/__init__.py

@@ -587,7 +587,7 @@ def CPyExtType(name, code, **kwargs):
         {tp_iternext},              /* tp_iternext */
         {name}_methods,             /* tp_methods */
         {name}_members,             /* tp_members */
-        0,                          /* tp_getset */
+        {tp_getset},                /* tp_getset */
         {tp_base},                  /* tp_base */
         {tp_dict},                  /* tp_dict */
         {tp_descr_get},             /* tp_descr_get */

graalpython/com.oracle.graal.python.test/src/tests/cpyext/test_object.py

@@ -370,6 +370,9 @@ class TestNoDictoffsetSubclass(TestNoDictoffset):
         obj.__dict__["newAttr"] = 123
         assert obj.newAttr == 123, "invalid attr"
 
+        obj.__dict__ = {'a': 1}
+        assert obj.a == 1
+
     def ignore_test_float_subclass(self):
         TestFloatSubclass = CPyExtType("TestFloatSubclass",
                                        """