fix: type checking in tests

tests/test_gridscan_decision.py

@@ -31,13 +31,14 @@ def _synthetic_scan(ny_n=20, nx_n=20):
     return {"file_prefix": "decision-test", "images": images}
 
 
-def test_decision_round_trips_without_pictures():
-    th = Thresholds()
+def test_decision_round_trips_without_pictures(request):
+    th = Thresholds.model_validate({})
     r = analyse(_synthetic_scan(), {"step_x_um": 10.0, "step_y_um": 10.0}, thresholds=th)
     assert r.found
     assert r.contour_cells, "the chosen 50 % blob must ship its cells"
     assert all(0 <= x < r.n_fast and 0 <= y < r.n_slow for x, y in r.contour_cells)
     # the centre lies within the contour's bounding box
+    assert r.centre is not None
     xs = [x for x, _ in r.contour_cells]
     ys = [y for _, y in r.contour_cells]
     assert min(xs) - 1 <= r.centre.nx <= max(xs) + 1
@@ -54,8 +55,9 @@ def test_decision_round_trips_without_pictures():
     assert "jpeg" not in wire["result"], "pictures never ride the JSON"
     assert wire["result"]["centre"]["image_number"] == r.centre.image_number
     assert wire["thresholds"]["object_union_spots"] is True
-
     back = GridScanDecision.model_validate(wire)
+    assert back.result.centre is not None
+    assert back.result.contour_cells is not None
     assert back.result.centre.nx == r.centre.nx
     assert [tuple(c) for c in back.result.contour_cells] == r.contour_cells