new_contents: #!/usr/bin/env python3
  import unittest
  from selfdrive.car.fingerprints import all_known_cars
  from selfdrive.car.car_helpers import interfaces
  from selfdrive.car.fingerprints import _FINGERPRINTS as FINGERPRINTS
  
  
  class TestCarParam(unittest.TestCase):
    def test_creating_car_params(self):
      all_cars = all_known_cars()
  
      for car in all_cars:
        fingerprint = FINGERPRINTS[car][0]
  
        CarInterface, CarController, CarState = interfaces[car]
        fingerprints = {
          0: fingerprint,
          1: fingerprint,
          2: fingerprint,
        }
  
        car_fw = []
  
        for has_relay in [True, False]:
          car_params = CarInterface.get_params(car, fingerprints, has_relay, car_fw)
          car_interface = CarInterface(car_params, CarController, CarState), car_params
  
          assert car_params
          assert car_interface
  
  
  if __name__ == "__main__":
    unittest.main()
  
subject: Add test that gets all the car params