read permissions on every GET

tests/test_plugins/test_supply_history.py

@@ -299,10 +299,10 @@ def test_no_estimate_never_reaches_the_order_list():
     assert orderlist([cartridge(None)]) == []
 
 
-def test_forecast_endpoint_says_so_when_zabbix_is_absent(client, db):
+def test_forecast_endpoint_says_so_when_zabbix_is_absent(client, db, auth_headers):
     """A dashboard must be told the data is missing, not shown an empty list
     that reads as 'nothing runs out soon'."""
-    response = client.get('/api/printers/supplies/forecast')
+    response = client.get('/api/printers/supplies/forecast', headers=auth_headers)
 
     assert response.status_code == 200
     body = response.get_json()['data']