def test1(self):

        gearbox = GearboxCost()

        gearbox.gearbox_mass = 30237.60
        gearbox.year = 2009
        gearbox.month = 12
        gearbox.drivetrain_design = "geared"

        check_gradient_unit_test(self, gearbox)
    def test1(self):

        gearbox = GearboxCost()

        gearbox.gearbox_mass = 30237.60
        gearbox.year = 2009
        gearbox.month = 12
        gearbox.drivetrain_design = 'geared'

        check_gradient_unit_test(self, gearbox)