def test_extract_YYYYMMDD(self): """extract_YYYYMMDD() should give known results""" filenames = ['rbspa_rel02_ect-hope-PA-L3_20130906_v4.0.0.cdf', 'rbspa_def_MagEphem_OP77Q_20150202_v1.0.0.h5', '20150204_firebird-2-fu3_T89D_MagEphem.h5', '20150202_firebird-2-fu3_T89D_MagEphem.h5', 'I_am_a_file_with_no_date.h5'] ans = [datetime.datetime(2013, 9, 6), datetime.datetime(2015, 2, 2), datetime.datetime(2015, 2, 4), datetime.datetime(2015, 2, 2), None] for tst, ans in zip(filenames, ans): self.assertEqual(ans, t.extract_YYYYMMDD(tst))