def fixtureid_cpcs(fixture_value):
    """
    Return a fixture ID to be used by pytest, for fixtures returning a list of
    CPCs.

    Parameters:
      * fixture_value (list of zhmcclient.Cpc): The list of CPCs.
    """
    cpc_list = fixture_value
    assert isinstance(cpc_list, list)
    cpcs_str = ','.join([cpc.name for cpc in cpc_list])
    return "CPCs={}".format(cpcs_str)