def test_add_property(self): fs = FieldSelector(["foo", "bar"]) self.assertEqual(fs.selectors, ["foo", "bar"]) fs.add_property("prop_name") self.assertEqual(fs.selectors, ["foo", "bar", "prop_name"]) with self.assertRaisesRegexp( ValueError, "properties must be specified by their string name", ): fs.add_property({}) self.assertEqual(fs.selectors, ["foo", "bar", "prop_name"])