Test check: la quota non prodotta entra come NaN/fail

Refs #118

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

src/backend/tests/test_task_acquisition.py

@@ -244,7 +244,7 @@ async def test_check_calibration_reasons(
 
 
 @pytest.mark.asyncio
-async def test_check_omits_quotes_the_graph_did_not_produce(
+async def test_check_lists_quotes_the_graph_did_not_produce_as_nan(
     client, db_session, measurement_tec_user, monkeypatch,
 ):
     _, task = await _camera_task(db_session, measurement_tec_user.id)
@@ -255,7 +255,10 @@ async def test_check_omits_quotes_the_graph_did_not_produce(
     monkeypatch.setattr("src.backend.services.vision_service._call_worker", fake_call)
     resp = await _check(client, measurement_tec_user, task)
     assert resp.status_code == 200  # un'anteprima non da' 422 a ogni frame
-    assert resp.json()["measurements"] == []
+    # #118: la quota non prodotta c'e', value null (NaN) e fail
+    measurements = resp.json()["measurements"]
+    assert len(measurements) == 1
+    assert measurements[0]["value"] is None and measurements[0]["pass_fail"] == "fail"
     assert resp.json()["failures"] == [{"tool_name": "blob"}]