def testExtraFileColumn(self):
    # Uncomment the code in assertLoadAndCheckExtraValues to generate this
    # string.
    self.SetArchiveContents(
        "routes.txt",
        "route_id,agency_id,route_short_name,route_long_name,route_type,"
        "t_foo,n_foo\n"
        "AB,DTA,,Airport Bullfrog,3,,\n"
        "t,DTA,T,,3,foo,\n"
        "n,DTA,N,,3,,bar\n")
    load1_problems = util.GetTestFailureProblemReporter(
        self, ("ExpirationDate", "UnrecognizedColumn"))
    schedule = self.MakeLoaderAndLoad(problems=load1_problems)
    saved_schedule_file = StringIO()
    schedule.WriteGoogleTransitFeed(saved_schedule_file)

    self.assertLoadAndCheckExtraValues(saved_schedule_file)
Extra columns loaded from a file are preserved when writing.
dataset/ETHPy150Open google/transitfeed/tests/transitfeed/testroute.py/RouteMemoryZipTestCase.testExtraFileColumn