test_onroad: more precise frame ID check (#38647)

openpilot/selfdrive/test/test_onroad.py

@@ -335,13 +335,14 @@ class TestOnroad(OpenpilotTestCase):
             assert np.all(eof_sof_diff > 0)
             assert np.all(eof_sof_diff < 50*1e6)
 
-        # TODO: loggerd doesn't start fast enough to be ready before the first frames come out
         first_fid = {min(self.ts[c]['frameId']) for c in cams}
-        #assert len(first_fid) == 1, "Cameras don't start on same frame ID"
         if cams[0].endswith('CameraState'):
           # camerad guarantees that all cams start on frame ID 0
           # (note loggerd also needs to start up fast enough to catch it)
           assert min(first_fid) < 100, "Cameras start on frame ID too high"
+        else:
+          # encoderd synchronizes all camera encoders to the same starting frame
+          assert len(first_fid) == 1, "Camera encoders don't start on same frame ID"
 
         # we don't do a full segment rotation, so these might not match exactly
         last_fid = {max(self.ts[c]['frameId']) for c in cams}