def test_data_persistance(self): s = XmlStorageBackend(self.filename) self.assertEqual(len(s), 0) s.set('mykeys', 'myvalues') self.assertEqual(len(s), 1) s = XmlStorageBackend(self.filename) self.assertEqual(len(s), 1) self.assertEqual(s.get('mykeys'), 'myvalues') self.assertEqual(len(s), 1) del s['mykeys'] self.assertEqual(len(s), 0) s = XmlStorageBackend(self.filename) self.assertRaises(KeyError, s.get, 'mykeys') self.assertEqual(len(s), 0)