def test_can_update_expression_system(self):
file_ = File()
file_._expression_system = "ABC"
file_.expression_system = "DEF"
self.assertEqual(file_._expression_system, "DEF")
def test_can_get_expression_system(self):
file_ = File()
file_._expression_system = "ABC"
self.assertIs(file_._expression_system, file_.expression_system)