Expand Flutter app scaffold

app/test/features/push/baron_safe_push_service_test.dart

@@ -0,0 +1,37 @@
+import 'package:baron_safe_app/src/features/push/baron_safe_push_models.dart';
+import 'package:baron_safe_app/src/features/push/baron_safe_push_service.dart';
+import 'package:flutter_test/flutter_test.dart';
+
+void main() {
+  group('PlaceholderBaronSafePushService', () {
+    test('registers the current placeholder token', () async {
+      const service = PlaceholderBaronSafePushService();
+
+      final result = await service.registerCurrentToken();
+
+      expect(result.registered, isTrue);
+      expect(result.token?.token, 'placeholder-push-token');
+      expect(result.token?.platform, BaronSafePushPlatform.unknown);
+    });
+
+    test('reports unavailable token without registration', () async {
+      const service = PlaceholderBaronSafePushService(
+        tokenProvider: _EmptyPushTokenProvider(),
+      );
+
+      final result = await service.registerCurrentToken();
+
+      expect(result.registered, isFalse);
+      expect(result.token, isNull);
+    });
+  });
+}
+
+class _EmptyPushTokenProvider implements BaronSafePushTokenProvider {
+  const _EmptyPushTokenProvider();
+
+  @override
+  Future<BaronSafePushToken?> readCurrentToken() async {
+    return null;
+  }
+}