def METHOD_NAME(dans_grid1):
    """Test variable Qin field."""
    Qin_local = np.zeros(25, dtype=float)
    Qin_local[13] = 2.0
    dans_grid1.mg.add_field("water__unit_flux_in", Qin_local, at="node", units="m**3/s")
    fr = FlowAccumulator(dans_grid1.mg, flow_director="D8")
    fr.run_one_step()
    Qout_local = np.zeros_like(Qin_local)
    Qout_local[10:14] = 200.0
    assert_array_equal(Qout_local, dans_grid1.mg.at_node["surface_water__discharge"])
    assert_array_equal(dans_grid1.A_target, dans_grid1.mg.at_node["drainage_area"])