'Verify tx and rx files that should be in sync.
:param tx_objs: sender diskfiles
:param policy: storage policy instance
:param tx_frag_index: the fragment index of tx diskfiles that should
have been used as a source for sync\'ing
:param rx_frag_index: the fragment index of expected rx diskfiles'

def _verify_ondisk_files(self, tx_objs, policy, tx_frag_index=None, rx_frag_index=None):

    for (o_name, diskfiles) in tx_objs.items():
        for tx_df in diskfiles:
            tx_df.open()
            if ((tx_frag_index is None) or (tx_df._frag_index == tx_frag_index)):
                rx_df = self._open_rx_diskfile(o_name, policy, rx_frag_index)
                match_etag = (tx_frag_index == rx_frag_index)
                self._verify_diskfile_sync(tx_df, rx_df, rx_frag_index, match_etag)
            else:
                self.assertRaises(DiskFileNotExist, self._open_rx_diskfile, o_name, policy, frag_index=tx_df._frag_index)
