snackBar should paint above the bottomSheet (#73558)

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

@@ -3031,6 +3031,25 @@ class ScaffoldState extends State<Scaffold> with TickerProviderStateMixin, Resto
       'the preferred API instead of the Scaffold methods.'
     );
 
+    if (_currentBottomSheet != null || _dismissedBottomSheets.isNotEmpty) {
+      final Widget stack = Stack(
+        alignment: Alignment.bottomCenter,
+        children: <Widget>[
+          ..._dismissedBottomSheets,
+          if (_currentBottomSheet != null) _currentBottomSheet!._widget,
+        ],
+      );
+      _addIfNonNull(
+        children,
+        stack,
+        _ScaffoldSlot.bottomSheet,
+        removeLeftPadding: false,
+        removeTopPadding: true,
+        removeRightPadding: false,
+        removeBottomPadding: _resizeToAvoidBottomInset,
+      );
+    }
+
     // SnackBar set by ScaffoldMessenger
     if (_messengerSnackBar != null) {
       final SnackBarBehavior snackBarBehavior = _messengerSnackBar?._widget.behavior
@@ -3110,25 +3129,6 @@ class ScaffoldState extends State<Scaffold> with TickerProviderStateMixin, Resto
       );
     }
 
-    if (_currentBottomSheet != null || _dismissedBottomSheets.isNotEmpty) {
-      final Widget stack = Stack(
-        alignment: Alignment.bottomCenter,
-        children: <Widget>[
-          ..._dismissedBottomSheets,
-          if (_currentBottomSheet != null) _currentBottomSheet!._widget,
-        ],
-      );
-      _addIfNonNull(
-        children,
-        stack,
-        _ScaffoldSlot.bottomSheet,
-        removeLeftPadding: false,
-        removeTopPadding: true,
-        removeRightPadding: false,
-        removeBottomPadding: _resizeToAvoidBottomInset,
-      );
-    }
-
     _addIfNonNull(
       children,
       _FloatingActionButtonTransition(

packages/flutter/test/material/snack_bar_test.dart

@@ -2266,4 +2266,29 @@ void main() {
     final AssertionError error = exceptions.first as AssertionError;
     expect(error.message, contains('Only one API should be used to manage SnackBars.'));
   });
+
+  testWidgets('SnackBars should be shown above the bottomSheet', (WidgetTester tester) async {
+    await tester.pumpWidget(const MaterialApp(
+      home: Scaffold(
+        bottomSheet: SizedBox(
+          width: 200,
+          height: 50,
+          child: ColoredBox(
+            color: Colors.pink,
+          ),
+        ),
+      ),
+    ));
+
+    final ScaffoldMessengerState scaffoldMessengerState = tester.state(find.byType(ScaffoldMessenger));
+    scaffoldMessengerState.showSnackBar(SnackBar(
+      content: const Text('I love Flutter!'),
+      duration: const Duration(seconds: 2),
+      action: SnackBarAction(label: 'ACTION', onPressed: () {}),
+      behavior: SnackBarBehavior.floating,
+    ));
+    await tester.pumpAndSettle(); // Have the SnackBar fully animate out.
+
+    await expectLater(find.byType(MaterialApp), matchesGoldenFile('snack_bar.goldenTest.workWithBottomSheet.png'));
+  });
 }