new_contents: import unittest
  
  class TestUpdict(unittest.TestCase):
  
      def makeone(self):
          from cheeseprism.desc import updict
          self.seed = dict(default=True)
  
          class Obj(object):
              attr = updict(self.seed)
  
          self.klass = Obj
          return Obj()
  
      def setUp(self):
          self.test_obj = self.makeone()
      
      def test_get(self):
          assert 'default' in self.test_obj.attr
          assert self.klass.attr is self.test_obj.attr
  
      def test_set(self):
          self.test_obj.attr = dict(add=1)
          assert 'add' in self.test_obj.attr
  
      def test_del(self):
          self.test_obj.attr = dict(add=1)
          assert 'add' in self.test_obj.attr
          del self.test_obj.attr
          assert not 'add' in self.test_obj.attr
  
subject: add a test to cover descriptors