expose route settings for showModalBottomSheet (#60640)

packages/flutter/lib/src/material/bottom_sheet.dart

@@ -583,6 +583,10 @@ class _BottomSheetSuspendedCurve extends ParametricCurve<double> {
 /// parameters can be passed in to customize the appearance and behavior of
 /// modal bottom sheets.
 ///
+/// The optional `routeSettings` parameter sets the [RouteSettings] of the modal bottom sheet
+/// sheet. This is particularly useful in the case that a user wants to observe
+/// [PopupRoute]s within a [NavigatorObserver].
+///
 /// Returns a `Future` that resolves to the value (if any) that was passed to
 /// [Navigator.pop] when the modal bottom sheet was closed.
 ///
@@ -648,6 +652,7 @@ Future<T> showModalBottomSheet<T>({
   bool useRootNavigator = false,
   bool isDismissible = true,
   bool enableDrag = true,
+  RouteSettings routeSettings,
 }) {
   assert(context != null);
   assert(builder != null);
@@ -670,6 +675,7 @@ Future<T> showModalBottomSheet<T>({
     isDismissible: isDismissible,
     modalBarrierColor: barrierColor,
     enableDrag: enableDrag,
+    settings: routeSettings,
   ));
 }
 

packages/flutter/test/material/bottom_sheet_test.dart

@@ -696,6 +696,38 @@ void main() {
     // the BottomNavigationBar.
     expect(tester.getBottomLeft(find.byType(BottomSheet)).dy, 600.0);
   });
+
+  testWidgets('Verify that route settings can be set in the showModalBottomSheet',
+      (WidgetTester tester) async {
+    final GlobalKey<ScaffoldState> scaffoldKey = GlobalKey<ScaffoldState>();
+    const RouteSettings routeSettings =
+        RouteSettings(name: 'route_name', arguments: 'route_argument');
+
+    await tester.pumpWidget(MaterialApp(
+      home: Scaffold(
+        key: scaffoldKey,
+        body: const Center(child: Text('body')),
+      ),
+    ));
+
+    RouteSettings retrievedRouteSettings;
+
+    showModalBottomSheet<void>(
+      context: scaffoldKey.currentContext,
+      routeSettings: routeSettings,
+      builder: (BuildContext context) {
+        retrievedRouteSettings = ModalRoute.of(context).settings;
+        return Container(
+          child: const Text('BottomSheet'),
+        );
+      },
+    );
+
+    await tester.pump();
+    await tester.pump(const Duration(seconds: 1));
+
+    expect(retrievedRouteSettings, routeSettings);
+  });
 }
 
 class _TestPage extends StatelessWidget {