def METHOD_NAME():
    """
    test one time step with uncertainty on the spill
    checks there is non-zero motion.
    """
    pSpill = sample_sc_release(num_le, start_pos, rel_time,
                               uncertain=True)
    cats = CatsMover(curr_file, tide=td)
    u_delta = _uncertain_loop(pSpill, cats)
    _assert_move(u_delta)