def METHOD_NAME(self):
    if getattr(dbm._defaultmod, 'library', None) == 'Berkeley DB':
        self.skipTest("Berkeley DB doesn't distinguish the empty value "
                      "from the absent one")
    f = dbm.open(_fname, 'c')
    self.assertEqual(f.keys(), [])
    f[b'empty'] = b''
    self.assertEqual(f.keys(), [b'empty'])
    self.assertIn(b'empty', f)
    self.assertEqual(f[b'empty'], b'')
    self.assertEqual(f.get(b'empty'), b'')
    self.assertEqual(f.setdefault(b'empty'), b'')
    f.close()