Fixes setting the correct locale to contexts with navigatorKey

CHANGELOG.md

@@ -4,6 +4,8 @@
 
 ### Fixes 
 
+- Fixes setting the correct locale to contexts with navigatorKey ([#1724](https://github.com/getsentry/sentry-dart/pull/1724))
+  - If you have a selected locale in e.g MaterialApp, this fix will retrieve the correct locale in the event context.
 - Unsupported types with Expando ([#1690](https://github.com/getsentry/sentry-dart/pull/1690))
 
 ### Features

flutter/lib/src/event_processor/flutter_enricher_event_processor.dart

@@ -5,6 +5,7 @@ import 'package:flutter/foundation.dart';
 import 'package:flutter/material.dart';
 import 'package:sentry/sentry.dart';
 
+import '../localizations.dart';
 import '../navigation/sentry_navigator_observer.dart';
 import '../sentry_flutter_options.dart';
 
@@ -107,7 +108,9 @@ class FlutterEnricherEventProcessor implements EventProcessor {
   }
 
   SentryCulture _getCulture(SentryCulture? culture) {
-    final languageTag = _window?.locale.toLanguageTag();
+    final windowLanguageTag = _window?.locale.toLanguageTag();
+    final screenLocale = retrieveWidgetLocale(_options.navigatorKey);
+    final languageTag = screenLocale?.toLanguageTag() ?? windowLanguageTag;
 
     // Future enhancement:
     // _window?.locales

flutter/lib/src/localizations.dart

@@ -0,0 +1,11 @@
+import 'package:flutter/cupertino.dart';
+import 'package:meta/meta.dart';
+
+@internal
+Locale? retrieveWidgetLocale(GlobalKey<NavigatorState>? navigatorKey) {
+  final BuildContext? context = navigatorKey?.currentContext;
+  if (context != null) {
+    return Localizations.maybeLocaleOf(context);
+  }
+  return null;
+}

flutter/lib/src/sentry_flutter_options.dart

@@ -286,4 +286,7 @@ class SentryFlutterOptions extends SentryOptions {
     // ignore: invalid_use_of_internal_member
     super.profilesSampleRate = value;
   }
+
+  /// The navigatorKey used to retrieve the current context of the app.
+  GlobalKey<NavigatorState>? navigatorKey;
 }

flutter/pubspec.yaml

@@ -29,6 +29,8 @@ dev_dependencies:
   flutter_lints: ^2.0.0
   collection: ^1.16.0
   remove_from_coverage: ^2.0.0
+  flutter_localizations:
+    sdk: flutter
 
 flutter:
   plugin:

flutter/test/event_processor/flutter_enricher_event_processor_test.dart

@@ -1,9 +1,11 @@
 import 'dart:async';
 
 import 'package:flutter/foundation.dart';
+
 // backcompatibility for Flutter < 3.3
 // ignore: unnecessary_import
 import 'package:flutter/material.dart';
+import 'package:flutter_localizations/flutter_localizations.dart';
 import 'package:flutter_test/flutter_test.dart';
 import 'package:package_info_plus/package_info_plus.dart';
 import 'package:sentry_flutter/sentry_flutter.dart';
@@ -73,6 +75,38 @@ void main() {
       expect(culture?.timezone, isNotNull);
     });
 
+    testWidgets(
+        'GIVEN MaterialApp WHEN setting locale and sentryNavigatorKey THEN enrich event culture with selected locale',
+        (WidgetTester tester) async {
+      GlobalKey<NavigatorState> navigatorKey = GlobalKey<NavigatorState>();
+
+      await tester.pumpWidget(MaterialApp(
+        navigatorKey: navigatorKey,
+        home: Material(),
+        localizationsDelegates: const [
+          GlobalMaterialLocalizations.delegate,
+          GlobalCupertinoLocalizations.delegate,
+        ],
+        supportedLocales: const [
+          Locale('en', 'US'),
+          Locale('de', 'DE'),
+        ],
+        locale: const Locale('de', 'DE'),
+      ));
+
+      final enricher = fixture.getSut(
+        binding: () => tester.binding,
+        optionsBuilder: (options) {
+          options.navigatorKey = navigatorKey;
+          return options;
+        },
+      );
+
+      final event = await enricher.apply(SentryEvent());
+
+      expect(event?.contexts.culture?.locale, 'de-DE');
+    });
+
     testWidgets('app context in foreground', (WidgetTester tester) async {
       final enricher = fixture.getSut(
         binding: () => tester.binding,
@@ -349,16 +383,19 @@ class Fixture {
     PlatformChecker? checker,
     bool hasNativeIntegration = false,
     bool reportPackages = true,
+    SentryFlutterOptions Function(SentryFlutterOptions)? optionsBuilder,
   }) {
     final platformChecker = checker ??
         MockPlatformChecker(
           hasNativeIntegration: hasNativeIntegration,
         );
+
     final options = SentryFlutterOptions(
       dsn: fakeDsn,
       checker: platformChecker,
     )..reportPackages = reportPackages;
-    return FlutterEnricherEventProcessor(options);
+    final customizedOptions = optionsBuilder?.call(options) ?? options;
+    return FlutterEnricherEventProcessor(customizedOptions);
   }
 
   PageRoute<dynamic> route(RouteSettings? settings) => PageRouteBuilder<void>(