Enhance YAML validation 🛠️: Add airline checks

Closes: #186

validate_yaml.py

@@ -29,10 +29,12 @@ def check_trips() -> None:
     print(len(routes), "routes")
 
 
-def check_flights() -> None:
+def check_flights(airlines: set[str]) -> None:
     """Check flights."""
-    flights = agenda.travel.parse_yaml("flights", data_dir)
-    print(len(flights), "flights")
+    bookings = agenda.travel.parse_yaml("flights", data_dir)
+    for booking in bookings:
+        assert all(flight["airline"] in airlines for flight in booking["flights"])
+    print(len(bookings), "flights")
 
 
 def check_trains() -> None:
@@ -103,25 +105,29 @@ def check_stations() -> None:
         assert agenda.get_country(station["country"])
 
 
-def check_airlines() -> None:
+def check_airlines() -> list[agenda.types.StrDict]:
     """Check airlines."""
     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
+
+    return airlines
 
 
 def check() -> None:
     """Validate personal data YAML files."""
+    airlines = check_airlines()
     check_trips()
-    check_flights()
+    check_flights({airline["iata"] for airline in airlines})
     check_trains()
     check_conferences()
     check_events()
     check_accommodation()
     check_airports()
     check_stations()
-    check_airlines()
 
 
 if __name__ == "__main__":