def METHOD_NAME(self, sel_mock):
    sel_mock.return_value = [10, 20]
    jdata = {"model": {"descriptor": {"type": "se_e2_a", "rcut": 6, "sel": "auto"}}}
    expected_out = {
        "model": {"descriptor": {"type": "se_e2_a", "rcut": 6, "sel": [12, 24]}}
    }
    jdata = update_sel(jdata)
    self.assertEqual(jdata, expected_out)