Prefer ICAO flight number for some airlines

validate_yaml.py

@@ -162,9 +162,19 @@ def check_airlines() -> list[agenda.types.StrDict]:
     airlines = agenda.travel.parse_yaml("airlines", data_dir)
     print(len(airlines), "airlines")
     for airline in airlines:
-        assert airline.keys() == {"icao", "iata", "name"}
-        assert len(airline["icao"]) == 3
-        assert len(airline["iata"]) == 2
+        try:
+            keys = set(airline.keys())
+            keys.discard("flight_number_prefer_icao")
+            assert keys == {"icao", "iata", "name"}
+            iata, icao = airline["iata"], airline["icao"]
+            assert iata[0].isupper() and iata[1].isupper() or iata[1].isdigit()
+            assert icao.isupper()
+            assert len(iata) == 2 and len(icao) == 3
+            if "flight_number_prefer_icao" in airline:
+                assert isinstance(airline["flight_number_prefer_icao"], bool)
+        except AssertionError:
+            print(yaml.dump([airline]))
+            raise
 
     return airlines