def METHOD_NAME(self):
    x = np.array([1, 1])
    y = np.array([0, 1])
    f_ = self._lensmodel.arrival_time(x, y, self.kwargs_lens)
    f_num = self._lens_model_interp.arrival_time(x, y, self.kwargs_lens_interp)
    npt.assert_almost_equal(f_num[0] - f_num[1], f_[0] - f_[1], decimal=1)
    lens_model, kwargs_lens = self.lightCone.cone_instance(
        z_source=self._z_source, cosmo=self._cosmo, multi_plane=True
    )
    f_cone = lens_model.arrival_time(x, y, kwargs_lens)
    npt.assert_almost_equal(f_cone[0] - f_cone[1], f_[0] - f_[1], decimal=1)