def METHOD_NAME(self):
    rec = self.matrices.get_record("omx2")
    with self.assertRaises(ValueError):
        rec.name = "omx"
    with self.assertRaises(ValueError):
        rec.file_name = "sfalls_skims.omx"
    rec.file_name = "SiouxFalls.omx"
    self.assertEqual(rec.cores, 1, "Setting a file that exists did not correct the number of cores")