def METHOD_NAME(si, nch_and_spacing):
    """basic total power check of the channel comb generation"""
    nb_channel = nch_and_spacing[0]
    p_tot = sum(si.signal + si.ase + si.nli)
    expected_p_tot = si.signal[0] * nb_channel
    assert pytest.approx(expected_p_tot, abs=0.01) == p_tot