def METHOD_NAME():
    """
    test one time step with no uncertainty on the spill
    checks there is non-zero motion.
    also checks the motion is same for all LEs
    """
    pSpill = sample_sc_release(num_le, start_pos, rel_time)
    wind = ShipDriftMover(wind_file, topology_file, grid_type=2)
    delta = _certain_loop(pSpill, wind)
    _assert_move(delta)
    # set windage to be constant or each particle has a different position,
    # doesn't work with uncertainty on
    # assert np.all(delta[:, 0] == delta[0, 0])  # lat move matches for all LEs
    # assert np.all(delta[:, 1] == delta[0, 1])  # long move matches for all LEs
    # returned delta is used in test_certain_uncertain test