add a shared chassis code test

selfdrive/car/volkswagen/tests/test_volkswagen.py

@@ -5,10 +5,17 @@ from openpilot.selfdrive.car.volkswagen.values import CAR
 
 
 class TestVolkswagenPlatformConfigs(unittest.TestCase):
-  def test_configs(self):
+  def test_chassis_codes(self):
     for platform in CAR:
       with self.subTest(platform=platform):
-        self.assertTrue(len(platform.config.chassis_codes) > 0, "Chassis code not set")
+        self.assertTrue(len(platform.config.chassis_codes) > 0, "Chassis codes not set")
+
+        # No two platforms should share chassis codes
+        for comp in CAR:
+          if platform == comp:
+            continue
+          self.assertEqual(set(), platform.config.chassis_codes & comp.config.chassis_codes,
+                           f"Shared chassis codes: {comp}")
 
 
 if __name__ == "__main__":