ReferenceField now store ObjectId's by default rather than DBRef (#290)

tests/all_warnings/__init__.py

@@ -30,28 +30,6 @@ class AllWarnings(unittest.TestCase):
         # restore default handling of warnings
         warnings.showwarning = self.showwarning_default
 
-    def test_dbref_reference_field_future_warning(self):
-
-        class Person(Document):
-            name = StringField()
-            parent = ReferenceField('self')
-
-        Person.drop_collection()
-
-        p1 = Person()
-        p1.parent = None
-        p1.save()
-
-        p2 = Person(name="Wilson Jr")
-        p2.parent = p1
-        p2.save(cascade=False)
-
-        self.assertTrue(len(self.warning_list) > 0)
-        warning = self.warning_list[0]
-        self.assertEqual(FutureWarning, warning["category"])
-        self.assertTrue("ReferenceFields will default to using ObjectId"
-                        in str(warning["message"]))
-
     def test_document_save_cascade_future_warning(self):
 
         class Person(Document):