diff --git a/selfdrive/car/tests/test_car_interfaces.py b/selfdrive/car/tests/test_car_interfaces.py
index 005ea114fd..3945fbb987 100755
--- a/selfdrive/car/tests/test_car_interfaces.py
+++ b/selfdrive/car/tests/test_car_interfaces.py
@@ -11,6 +11,7 @@ from common.realtime import DT_CTRL
 from selfdrive.car import gen_empty_fingerprint
 from selfdrive.car.car_helpers import interfaces
 from selfdrive.car.fingerprints import all_known_cars
+from selfdrive.car.interfaces import get_interface_attr
 from selfdrive.test.fuzzy_generation import DrawType, FuzzyGenerator
 
 
@@ -109,5 +110,31 @@ class TestCarInterfaces(unittest.TestCase):
        hasattr(radar_interface, '_update') and hasattr(radar_interface, 'trigger_msg'):
       radar_interface._update([radar_interface.trigger_msg])
 
+  def test_interface_attrs(self):
+    """Asserts basic behavior of interface attribute getter"""
+    num_brands = len(get_interface_attr('CAR'))
+    self.assertGreaterEqual(num_brands, 13)
+
+    # Should return value for all brands when not combining, even if attribute doesn't exist
+    ret = get_interface_attr('FAKE_ATTR')
+    self.assertEqual(len(ret), num_brands)
+
+    # Make sure we can combine dicts
+    ret = get_interface_attr('DBC', combine_brands=True)
+    self.assertGreaterEqual(len(ret), 170)
+
+    # We don't support combining non-dicts
+    ret = get_interface_attr('CAR', combine_brands=True)
+    self.assertEqual(len(ret), 0)
+
+    # If brand has None value, it shouldn't return when ignore_none=True is specified
+    none_brands = {b for b, v in get_interface_attr('FINGERPRINTS').items() if v is None}
+    self.assertGreaterEqual(len(none_brands), 1)
+
+    ret = get_interface_attr('FINGERPRINTS', ignore_none=True)
+    none_brands_in_ret = none_brands.intersection(ret)
+    self.assertEqual(len(none_brands_in_ret), 0, f'Brands with None values in ignore_none=True result: {none_brands_in_ret}')
+
+
 if __name__ == "__main__":
   unittest.main()