feat: Introduce comprehensive unit tests for models and BLoCs using mockito and bloc_test, and refine TripBloc error handling.

lib/blocs/trip/trip_bloc.dart

@@ -103,7 +103,12 @@ class TripBloc extends Bloc<TripEvent, TripState> {
               'Error loading trips: $error',
               stackTrace,
             );
-            emit(const TripError('Impossible de charger les voyages'));
+            add(
+              const _TripsUpdated(
+                [],
+                error: 'Impossible de charger les voyages',
+              ),
+            );
           },
         );
   }
@@ -117,7 +122,11 @@ class TripBloc extends Bloc<TripEvent, TripState> {
   ///   [event]: The _TripsUpdated event containing the updated trip list
   ///   [emit]: State emitter function
   void _onTripsUpdated(_TripsUpdated event, Emitter<TripState> emit) {
-    emit(TripLoaded(event.trips));
+    if (event.error != null) {
+      emit(TripError(event.error!));
+    } else {
+      emit(TripLoaded(event.trips));
+    }
   }
 
   /// Handles [TripCreateRequested] events.
@@ -234,16 +243,11 @@ class TripBloc extends Bloc<TripEvent, TripState> {
 ///
 /// This internal event is used to process updates from the trip stream
 /// subscription and emit appropriate states based on the received data.
+/// internal event
 class _TripsUpdated extends TripEvent {
-  /// List of trips received from the stream
   final List<Trip> trips;
-
-  /// Creates a _TripsUpdated event.
-  ///
-  /// Args:
-  ///   [trips]: List of trips from the stream update
-  const _TripsUpdated(this.trips);
-
+  final String? error;
+  const _TripsUpdated(this.trips, {this.error});
   @override
-  List<Object?> get props => [trips];
+  List<Object?> get props => [trips, error];
 }