[go_router] Add maybePop for safe navigation pops

packages/go_router/.gitignore

@@ -28,3 +28,4 @@ migrate_working_dir/
 .dart_tool/
 .packages
 build/
+/coverage/

packages/go_router/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 17.4.0
+
+- Adds `maybePop` to `GoRouter`, `GoRouterDelegate`, and `GoRouterHelper`. This method mirrors [Navigator.maybePop] and [BackButton] by returning `false` instead of throwing when there is nothing to pop, and calls [GoRouter.restore] when a pop completes synchronously.
+
 ## 17.3.0
 
 - Updates minimum supported SDK version to Flutter 3.38/Dart 3.10.

packages/go_router/lib/src/delegate.dart

@@ -56,6 +56,9 @@ class GoRouterDelegate extends RouterDelegate<RouteMatchList> with ChangeNotifie
   Future<bool> popRoute() async {
     final Iterable<NavigatorState> states = _findCurrentNavigators();
     for (final state in states) {
+      if (!state.mounted) {
+        continue;
+      }
       final bool didPop = await state.maybePop(); // Call maybePop() directly
       if (didPop) {
         return true; // Return true if maybePop handled the pop
@@ -103,6 +106,24 @@ class GoRouterDelegate extends RouterDelegate<RouteMatchList> with ChangeNotifie
     states.first.pop(result);
   }
 
+  /// Calls [NavigatorState.maybePop] on the current navigator stack.
+  ///
+  /// Returns `true` if a route was popped and `false` otherwise. This method
+  /// does not throw if there is nothing to pop.
+  Future<bool> maybePop<T extends Object?>([T? result]) async {
+    final Iterable<NavigatorState> states = _findCurrentNavigators();
+    for (final NavigatorState state in states) {
+      if (!state.mounted) {
+        continue;
+      }
+      final bool didPop = await state.maybePop<T>(result);
+      if (didPop) {
+        return true;
+      }
+    }
+    return false;
+  }
+
   /// Get a prioritized list of NavigatorStates,
   /// which either can pop or are exit routes.
   ///

packages/go_router/lib/src/misc/extensions.dart

@@ -67,6 +67,16 @@ extension GoRouterHelper on BuildContext {
   /// Returns `true` if there is more than 1 page on the stack.
   bool canPop() => GoRouter.of(this).canPop();
 
+  /// Pop the top page off the Navigator's page stack if possible.
+  ///
+  /// Returns `true` if a route was popped and `false` otherwise. This method
+  /// does not throw if there is nothing to pop.
+  ///
+  /// See also:
+  /// * [pop], which throws if there is nothing to pop.
+  /// * [canPop], which can be used to check whether a pop is possible.
+  Future<bool> maybePop<T extends Object?>([T? result]) => GoRouter.of(this).maybePop<T>(result);
+
   /// Pop the top page off the Navigator's page stack by calling
   /// [Navigator.pop].
   void pop<T extends Object?>([T? result]) => GoRouter.of(this).pop(result);

packages/go_router/lib/src/router.dart

@@ -552,6 +552,10 @@ class GoRouter implements RouterConfig<RouteMatchList> {
   ///
   /// Ensure that the `value` of `routeInformationProvider` is synced
   ///  with `routerDelegate.currentConfiguration`.
+  ///
+  /// See also:
+  /// * [maybePop], which returns `false` instead of throwing if there is
+  ///   nothing to pop.
   void pop<T extends Object?>([T? result]) {
     assert(() {
       log('popping ${routerDelegate.currentConfiguration.uri}');
@@ -566,6 +570,25 @@ class GoRouter implements RouterConfig<RouteMatchList> {
     }
   }
 
+  /// Pop the top-most route off the current screen if possible.
+  ///
+  /// This method calls [NavigatorState.maybePop] on the underlying navigators,
+  /// similar to [BackButton]. It returns `true` if a route was popped and
+  /// `false` otherwise. Unlike [pop], this method does not throw if there is
+  /// nothing to pop.
+  ///
+  /// When a pop completes synchronously, this method also calls [restore] to
+  /// keep the [routeInformationProvider] in sync with
+  /// [GoRouterDelegate.currentConfiguration].
+  Future<bool> maybePop<T extends Object?>([T? result]) async {
+    final RouteMatchList configBeforePop = routerDelegate.currentConfiguration;
+    final bool didPop = await routerDelegate.maybePop<T>(result);
+    if (didPop && !identical(routerDelegate.currentConfiguration, configBeforePop)) {
+      restore(routerDelegate.currentConfiguration);
+    }
+    return didPop;
+  }
+
   /// Refresh the route.
   void refresh() {
     assert(() {

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: 17.3.0
+version: 17.4.0
 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/delegate_test.dart

@@ -442,6 +442,111 @@ void main() {
       expect(goRouter.routerDelegate.currentConfiguration.matches.length, 0);
       expect(goRouter.routerDelegate.canPop(), false);
     });
+
+    testWidgets('It should return false on screen A and true on screen B after push', (
+      WidgetTester tester,
+    ) async {
+      final GoRouter goRouter = GoRouter(
+        initialLocation: '/a',
+        routes: <GoRoute>[
+          GoRoute(path: '/a', builder: (_, _) => const Text('Screen A')),
+          GoRoute(path: '/b', builder: (_, _) => const Text('Screen B')),
+        ],
+      );
+      addTearDown(goRouter.dispose);
+      await tester.pumpWidget(MaterialApp.router(routerConfig: goRouter));
+      await tester.pumpAndSettle();
+
+      expect(find.text('Screen A'), findsOneWidget);
+      expect(goRouter.routerDelegate.canPop(), isFalse);
+
+      goRouter.push('/b');
+      await tester.pumpAndSettle();
+
+      expect(find.text('Screen B'), findsOneWidget);
+      expect(goRouter.routerDelegate.canPop(), isTrue);
+
+      goRouter.pop();
+      await tester.pumpAndSettle();
+
+      expect(find.text('Screen A'), findsOneWidget);
+      expect(goRouter.routerDelegate.canPop(), isFalse);
+      expect(goRouter.routerDelegate.currentConfiguration.matches.length, 1);
+      expect(goRouter.routerDelegate.currentConfiguration.uri.path, '/a');
+    });
+
+    testWidgets('It should check shell navigator when root navigator cannot pop', (
+      WidgetTester tester,
+    ) async {
+      final shellNavigatorKey = GlobalKey<NavigatorState>();
+      final GoRouter goRouter = GoRouter(
+        initialLocation: '/a',
+        routes: <RouteBase>[
+          ShellRoute(
+            navigatorKey: shellNavigatorKey,
+            builder: (_, _, Widget child) => child,
+            routes: <GoRoute>[
+              GoRoute(path: '/a', builder: (_, _) => const Text('Screen A')),
+              GoRoute(path: '/b', builder: (_, _) => const Text('Screen B')),
+            ],
+          ),
+        ],
+      );
+      addTearDown(goRouter.dispose);
+      await tester.pumpWidget(MaterialApp.router(routerConfig: goRouter));
+      await tester.pumpAndSettle();
+
+      expect(goRouter.routerDelegate.canPop(), isFalse);
+      expect(goRouter.routerDelegate.navigatorKey.currentState?.canPop(), isFalse);
+
+      goRouter.push('/b');
+      await tester.pumpAndSettle();
+
+      expect(goRouter.routerDelegate.canPop(), isTrue);
+      expect(shellNavigatorKey.currentState?.canPop(), isTrue);
+      expect(goRouter.routerDelegate.navigatorKey.currentState?.canPop(), isFalse);
+
+      goRouter.pop();
+      await tester.pumpAndSettle();
+
+      expect(find.text('Screen A'), findsOneWidget);
+      expect(goRouter.routerDelegate.canPop(), isFalse);
+      expect(shellNavigatorKey.currentState?.canPop(), isFalse);
+    });
+  });
+
+  group('willHandlePopInternally', () {
+    testWidgets('does not remove route when page handles pop internally', (
+      WidgetTester tester,
+    ) async {
+      final GoRouter goRouter = GoRouter(
+        initialLocation: '/',
+        routes: <GoRoute>[
+          GoRoute(
+            path: '/',
+            builder: (_, _) => const Text('Home'),
+            routes: <GoRoute>[
+              GoRoute(
+                path: 'internal',
+                pageBuilder: (_, _) => const _InternalPopPage(),
+              ),
+            ],
+          ),
+        ],
+      );
+      addTearDown(goRouter.dispose);
+      await tester.pumpWidget(MaterialApp.router(routerConfig: goRouter));
+
+      goRouter.push('/internal');
+      await tester.pumpAndSettle();
+      expect(find.text('Internal'), findsOneWidget);
+
+      goRouter.pop();
+      await tester.pumpAndSettle();
+
+      expect(find.text('Internal'), findsOneWidget);
+      expect(find.text('Home'), findsNothing);
+    });
   });
 
   group('pushReplacement', () {
@@ -752,3 +857,45 @@ class _DummyStatefulWidgetState extends State<DummyStatefulWidget> {
   @override
   Widget build(BuildContext context) => Container();
 }
+
+class _InternalPopPage extends Page<void> {
+  const _InternalPopPage();
+
+  @override
+  Route<void> createRoute(BuildContext context) => _InternalPopRoute(this);
+}
+
+class _InternalPopRoute extends PageRoute<void> {
+  _InternalPopRoute(_InternalPopPage page) : super(settings: page);
+
+  @override
+  Color? get barrierColor => null;
+
+  @override
+  String? get barrierLabel => null;
+
+  @override
+  bool get opaque => true;
+
+  @override
+  bool get maintainState => true;
+
+  @override
+  Duration get transitionDuration => Duration.zero;
+
+  @override
+  bool get willHandlePopInternally => true;
+
+  @override
+  // ignore: must_call_super
+  bool didPop(void result) => false;
+
+  @override
+  Widget buildPage(
+    BuildContext context,
+    Animation<double> animation,
+    Animation<double> secondaryAnimation,
+  ) {
+    return const Text('Internal');
+  }
+}