def METHOD_NAME(self):
    rmg = RasterModelGrid((4, 5))
    rmg.at_node["topographic__elevation"] = -rmg.node_y
    slopes_out = rmg.calc_slope_at_node(
        rmg.at_node["topographic__elevation"], return_components=True
    )
    assert np.all(slopes_out[0] == approx(np.full(20, np.pi / 4.0, dtype=float)))
    assert np.all(
        slopes_out[1][1] == approx(np.full(20, -np.pi / 4.0, dtype=float))
    )
    assert np.all(slopes_out[1][0] == approx(np.zeros(20, dtype=float)))