Fix CLI JSON currency serialization (#101)

* fix: Preserve returned CLI JSON currency
Jira: PLAF-00000

* fix: Add round-trip currency regression test
Jira: PLAF-00000

Author: kvasdopil

fli/cli/utils.py

@@ -196,7 +196,7 @@ def _serialize_flight_segment_result(flight: Any, *, include_price: bool = False
     }
     if include_price:
         payload["price"] = flight.price
-        payload["currency"] = DEFAULT_CURRENCY
+        payload["currency"] = flight.currency or DEFAULT_CURRENCY
     return payload
 
 
@@ -206,7 +206,7 @@ def serialize_flight_result(flight_data: Any) -> dict[str, Any]:
         outbound, return_flight = flight_data
         return {
             "price": outbound.price,
-            "currency": DEFAULT_CURRENCY,
+            "currency": outbound.currency or DEFAULT_CURRENCY,
             "duration": outbound.duration + return_flight.duration,
             "stops": outbound.stops + return_flight.stops,
             "outbound": _serialize_flight_segment_result(outbound),
@@ -222,7 +222,7 @@ def serialize_date_result(date_result: Any, trip_type: TripType) -> dict[str, An
         "departure_date": date_result.date[0].date().isoformat(),
         "return_date": None,
         "price": date_result.price,
-        "currency": DEFAULT_CURRENCY,
+        "currency": date_result.currency or DEFAULT_CURRENCY,
     }
     if trip_type == TripType.ROUND_TRIP and len(date_result.date) > 1:
         payload["return_date"] = date_result.date[1].date().isoformat()

tests/cli/test_utils.py

@@ -337,3 +337,35 @@ def test_serialize_date_result_round_trip():
         "price": 599.98,
         "currency": "USD",
     }
+
+
+def test_serialize_flight_result_uses_returned_currency():
+    """JSON flight serialization should preserve the parsed result currency."""
+    flight = _make_flight_result(price=159.0, currency="SEK")
+
+    payload = serialize_flight_result(flight)
+
+    assert payload["currency"] == "SEK"
+
+
+def test_serialize_flight_result_round_trip_uses_returned_currency():
+    """Round-trip JSON serialization should preserve the parsed result currency."""
+    outbound = _make_flight_result(price=2534.0, currency="SEK", flight_number="SK101")
+    return_flight = _make_flight_result(price=2534.0, currency="SEK", flight_number="SK202")
+
+    payload = serialize_flight_result((outbound, return_flight))
+
+    assert payload["currency"] == "SEK"
+
+
+def test_serialize_date_result_uses_returned_currency():
+    """JSON date serialization should preserve the parsed result currency."""
+    result = DatePrice(
+        date=(datetime(2026, 5, 1),),
+        price=118.0,
+        currency="SEK",
+    )
+
+    payload = serialize_date_result(result, TripType.ONE_WAY)
+
+    assert payload["currency"] == "SEK"