[go_router] Add preload parameter to StatefulShellBranchData.$branch (flutter#8545)

Part of flutter/flutter#162055

The parameter will be used by `go_router_builder`

Author: ValentinVignal

packages/go_router/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 14.8.0
+
+- Adds `preload` parameter to `StatefulShellBranchData.$branch`.
+
 ## 14.7.2
 
 - Add missing `await` keyword to `onTap` callback in `navigation.md`.

packages/go_router/lib/src/route_data.dart

@@ -342,13 +342,15 @@ abstract class StatefulShellBranchData {
     List<NavigatorObserver>? observers,
     String? initialLocation,
     String? restorationScopeId,
+    bool preload = false,
   }) {
     return StatefulShellBranch(
       routes: routes,
       navigatorKey: navigatorKey,
       observers: observers,
       initialLocation: initialLocation,
       restorationScopeId: restorationScopeId,
+      preload: preload,
     );
   }
 }

packages/go_router/pubspec.yaml

@@ -1,7 +1,7 @@
 name: go_router
 description: A declarative router for Flutter based on Navigation 2 supporting
   deep linking, data-driven routes and more
-version: 14.7.2
+version: 14.8.0
 repository: https://github.com/flutter/packages/tree/main/packages/go_router
 issue_tracker: https://github.com/flutter/flutter/issues?q=is%3Aissue+is%3Aopen+label%3A%22p%3A+go_router%22
 

packages/go_router/test/route_data_test.dart

@@ -420,6 +420,21 @@ void main() {
     });
   });
 
+  group('StatefulShellBranchData', () {
+    test('Can assign preload', () {
+      final StatefulShellBranch branch = StatefulShellBranchData.$branch(
+        preload: true,
+        routes: <RouteBase>[
+          GoRouteData.$route(
+            path: '/child',
+            factory: (GoRouterState state) => const _GoRouteDataBuild(),
+          ),
+        ],
+      );
+      expect(branch.preload, true);
+    });
+  });
+
   testWidgets(
     'It should redirect using the overridden redirect method',
     (WidgetTester tester) async {