def METHOD_NAME(self):
    """Test MSTransferor private method _getPNNsFromPSNs()"""
    self.assertItemsEqual(self.msTransferor.psn2pnnMap, {})
    # now fill up the cache
    self.msTransferor.psn2pnnMap = self.msTransferor.cric.PSNtoPNNMap()
    self.assertItemsEqual(self.msTransferor._getPNNsFromPSNs([]), set())
    pnns = self.msTransferor._getPNNsFromPSNs(["T1_IT_CNAF", "T1_IT_CNAF_Disk"])
    self.assertItemsEqual(pnns, set(["T1_IT_CNAF_Disk"]))
    # dropping T3s and CERNBOX
    pnns = self.msTransferor._getPNNsFromPSNs(["T1_US_FNAL", "T2_CH_CERN_HLT"])
    self.assertItemsEqual(pnns, set(["T1_US_FNAL_Disk", "T2_CH_CERN"]))
    # testing with non-existant PSNs
    psns = self.msTransferor._getPNNsFromPSNs(["T1_US_FNAL_Disk", "T2_CH_CERNBOX"])
    self.assertItemsEqual(psns, set())