Monitor: quota con soli NaN resta in elenco con media null e fuori tolleranza

Refs #118

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

src/backend/tests/test_monitor.py

@@ -81,3 +81,29 @@ async def test_open_lists_only_open_runs_with_means(client, db_session, admin_us
 async def test_open_empty_for_admin(client, admin_user):
     resp = await client.get("/api/production-runs/open", headers=auth_headers(admin_user))
     assert resp.status_code == 200 and resp.json() == []
+
+
+async def test_nan_quotes_in_the_monitor(client, db_session, admin_user):
+    """#118: solo NaN -> la quota resta, mean null e fuori tolleranza; mista -> media dei numeri."""
+    sup = await _create_user(db_session, "capo", roles=["Supervisor"])
+    r1, s1, v1 = await _run(db_session, admin_user, "N1")
+    r2, s2, v2 = await _run(db_session, admin_user, "N2")
+    for i in range(2):
+        db_session.add(_m(r1, s1, v1, admin_user, None, "fail", i))
+    for i, (val, pf) in enumerate([(None, "fail"), (10.0, "pass"), (10.2, "pass")]):
+        db_session.add(_m(r2, s2, v2, admin_user, val, pf, i))
+    await db_session.commit()
+
+    resp = await client.get("/api/production-runs/open", headers=auth_headers(sup))
+    assert resp.status_code == 200
+    body = {r["station_code"]: r for r in resp.json()}
+    only_nan = body["ST-N1"]["subtasks"]
+    assert len(only_nan) == 1
+    assert only_nan[0]["mean"] is None
+    assert only_nan[0]["count"] == 2
+    assert only_nan[0]["in_tolerance"] is False
+    assert body["ST-N1"]["fail_count"] == 2
+    mixed = body["ST-N2"]["subtasks"][0]
+    assert mixed["count"] == 3
+    assert round(mixed["mean"], 6) == 10.1
+    assert mixed["in_tolerance"] is True