[go_router] Retain query parameter during refresh and first redirect (#5276)

Fixes https://github.com/flutter/flutter/issues/137513

packages/go_router/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 12.1.1
+
+- Retains query parameters during refresh and first redirect.
+
 ## 12.1.0
 
 - Adds an ability to add a custom codec for serializing/deserializing extra.

packages/go_router/lib/src/router.dart

@@ -531,10 +531,18 @@ class GoRouter implements RouterConfig<RouteMatchList> {
       // verified by assert() during the initialization.
       return initialLocation!;
     }
-    final Uri platformDefaultUri =
-        Uri.parse(WidgetsBinding.instance.platformDispatcher.defaultRouteName);
-    final String platformDefault =
-        platformDefaultUri.path.isEmpty ? '/' : platformDefaultUri.path;
+    Uri platformDefaultUri = Uri.parse(
+      WidgetsBinding.instance.platformDispatcher.defaultRouteName,
+    );
+    if (platformDefaultUri.hasEmptyPath) {
+      // TODO(chunhtai): Clean up this once `RouteInformation.uri` is available
+      // in packages repo.
+      platformDefaultUri = Uri(
+        path: '/',
+        queryParameters: platformDefaultUri.queryParameters,
+      );
+    }
+    final String platformDefault = platformDefaultUri.toString();
     if (initialLocation == null) {
       return platformDefault;
     } else if (platformDefault == '/') {

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: 12.1.0
+version: 12.1.1
 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/go_router_test.dart

@@ -2503,6 +2503,21 @@ void main() {
       TestWidgetsFlutterBinding.instance.platformDispatcher
           .clearDefaultRouteNameTestValue();
     });
+
+    testWidgets(
+        'When platformDispatcher.defaultRouteName is deep-link Uri with '
+        'scheme, authority, no path, and query parameters',
+        (WidgetTester tester) async {
+      TestWidgetsFlutterBinding.instance.platformDispatcher
+          .defaultRouteNameTestValue = 'https://domain.com?param=1';
+      final GoRouter router = await createRouter(
+        routes,
+        tester,
+      );
+      expect(router.routeInformationProvider.value.uri.toString(), '/?param=1');
+      TestWidgetsFlutterBinding.instance.platformDispatcher
+          .clearDefaultRouteNameTestValue();
+    });
   });
 
   group('params', () {