[go_router] Fixes deep-link with no path on cold start (#5113)

*List which issues are fixed by this PR. You must list at least one issue.*
- flutter/flutter#133928

*If you had to change anything in the [flutter/tests] repo, include a link to the migration guide as per the [breaking change policy].*
- No breaking changes

packages/go_router/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 12.0.1
+
+- Fixes deep-link with no path on cold start.
+
 ## 12.0.0
 
 - Adds ability to dynamically update routing table.

packages/go_router/lib/src/parser.dart

@@ -83,6 +83,9 @@ class GoRouteInformationParser extends RouteInformationParser<RouteMatchList> {
     initialMatches =
         // TODO(chunhtai): remove this ignore and migrate the code
         // https://github.com/flutter/flutter/issues/124045.
+        // TODO(chunhtai): After the migration from routeInformation's location
+        // to uri, empty path check might be required here; see
+        // https://github.com/flutter/packages/pull/5113#discussion_r1374861070
         // ignore: deprecated_member_use, unnecessary_non_null_assertion
         configuration.findMatch(routeInformation.location!, extra: state.extra);
     if (initialMatches.isError) {

packages/go_router/lib/src/router.dart

@@ -526,8 +526,10 @@ 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 =
-        WidgetsBinding.instance.platformDispatcher.defaultRouteName;
+        platformDefaultUri.path.isEmpty ? '/' : platformDefaultUri.path;
     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: 12.0.0
+version: 12.0.1
 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

@@ -2445,8 +2445,8 @@ void main() {
       // https://github.com/flutter/flutter/issues/124045.
       // ignore: deprecated_member_use
       expect(router.routeInformationProvider.value.location, '/dummy');
-      TestWidgetsFlutterBinding
-          .instance.platformDispatcher.defaultRouteNameTestValue = '/';
+      TestWidgetsFlutterBinding.instance.platformDispatcher
+          .clearDefaultRouteNameTestValue();
     });
 
     test('throws assertion if initialExtra is set w/o initialLocation', () {
@@ -2466,6 +2466,45 @@ void main() {
     });
   });
 
+  group('_effectiveInitialLocation()', () {
+    final List<GoRoute> routes = <GoRoute>[
+      GoRoute(
+        path: '/',
+        builder: (BuildContext context, GoRouterState state) =>
+            const HomeScreen(),
+      ),
+    ];
+
+    testWidgets(
+        'When platformDispatcher.defaultRouteName is deep-link Uri with '
+        'scheme, authority, no path', (WidgetTester tester) async {
+      TestWidgetsFlutterBinding.instance.platformDispatcher
+          .defaultRouteNameTestValue = 'https://domain.com';
+      final GoRouter router = await createRouter(
+        routes,
+        tester,
+      );
+      expect(router.routeInformationProvider.value.uri.path, '/');
+      TestWidgetsFlutterBinding.instance.platformDispatcher
+          .clearDefaultRouteNameTestValue();
+    });
+
+    testWidgets(
+        'When platformDispatcher.defaultRouteName is deep-link Uri with '
+        'scheme, authority, no path, but trailing slash',
+        (WidgetTester tester) async {
+      TestWidgetsFlutterBinding.instance.platformDispatcher
+          .defaultRouteNameTestValue = 'https://domain.com/';
+      final GoRouter router = await createRouter(
+        routes,
+        tester,
+      );
+      expect(router.routeInformationProvider.value.uri.path, '/');
+      TestWidgetsFlutterBinding.instance.platformDispatcher
+          .clearDefaultRouteNameTestValue();
+    });
+  });
+
   group('params', () {
     testWidgets('preserve path param case', (WidgetTester tester) async {
       final List<GoRoute> routes = <GoRoute>[