Fix a11y scrolling for reversed lists (#52332)

packages/flutter/lib/src/widgets/scroll_position.dart

@@ -447,15 +447,23 @@ abstract class ScrollPosition extends ViewportOffset with ScrollMetrics {
   void _updateSemanticActions() {
     SemanticsAction forward;
     SemanticsAction backward;
-    switch (axis) {
-      case Axis.vertical:
-        forward = SemanticsAction.scrollUp;
-        backward = SemanticsAction.scrollDown;
+    switch (axisDirection) {
+      case AxisDirection.up:
+        forward = SemanticsAction.scrollDown;
+        backward = SemanticsAction.scrollUp;
         break;
-      case Axis.horizontal:
+      case AxisDirection.right:
         forward = SemanticsAction.scrollLeft;
         backward = SemanticsAction.scrollRight;
         break;
+      case AxisDirection.down:
+        forward = SemanticsAction.scrollUp;
+        backward = SemanticsAction.scrollDown;
+        break;
+      case AxisDirection.left:
+        forward = SemanticsAction.scrollRight;
+        backward = SemanticsAction.scrollLeft;
+        break;
     }
 
     final Set<SemanticsAction> actions = <SemanticsAction>{};

packages/flutter/test/widgets/list_view_semantics_test.dart

+// Copyright 2014 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:flutter_test/flutter_test.dart';
+import 'package:flutter/widgets.dart';
+
+import 'semantics_tester.dart';
+
+void main() {
+  group('Available semantic scroll actions', () {
+    // Regression tests for https://github.com/flutter/flutter/issues/52032.
+
+    const int itemCount = 10;
+    const double itemHeight = 150.0;
+
+    testWidgets('forward vertical', (WidgetTester tester) async {
+      final SemanticsTester semantics = SemanticsTester(tester);
+      final ScrollController controller = ScrollController();
+
+      await tester.pumpWidget(
+        Directionality(
+          textDirection: TextDirection.ltr,
+          child: ListView.builder(
+            controller: controller,
+            itemCount: itemCount,
+            itemBuilder: (BuildContext context, int index) {
+              return SizedBox(
+                height: itemHeight,
+                child: Text('Tile $index'),
+              );
+            },
+          ),
+        ),
+      );
+
+      expect(semantics, includesNodeWith(actions: <SemanticsAction>[SemanticsAction.scrollUp]));
+
+      // Jump to the end.
+      controller.jumpTo(itemCount * itemHeight);
+      await tester.pumpAndSettle();
+      expect(semantics, includesNodeWith(actions: <SemanticsAction>[SemanticsAction.scrollDown]));
+
+      semantics.dispose();
+    });
+
+    testWidgets('reverse vertical', (WidgetTester tester) async {
+      final SemanticsTester semantics = SemanticsTester(tester);
+      final ScrollController controller = ScrollController();
+
+      await tester.pumpWidget(
+        Directionality(
+          textDirection: TextDirection.ltr,
+          child: ListView.builder(
+            reverse: true,
+            controller: controller,
+            itemCount: itemCount,
+            itemBuilder: (BuildContext context, int index) {
+              return SizedBox(
+                height: itemHeight,
+                child: Text('Tile $index'),
+              );
+            },
+          ),
+        ),
+      );
+
+      expect(semantics, includesNodeWith(actions: <SemanticsAction>[SemanticsAction.scrollDown]));
+
+      // Jump to the end.
+      controller.jumpTo(itemCount * itemHeight);
+      await tester.pumpAndSettle();
+      expect(semantics, includesNodeWith(actions: <SemanticsAction>[SemanticsAction.scrollUp]));
+
+      semantics.dispose();
+    });
+
+    testWidgets('forward horizontal', (WidgetTester tester) async {
+      final SemanticsTester semantics = SemanticsTester(tester);
+      final ScrollController controller = ScrollController();
+
+      await tester.pumpWidget(
+        Directionality(
+          textDirection: TextDirection.ltr,
+          child: ListView.builder(
+            scrollDirection: Axis.horizontal,
+            controller: controller,
+            itemCount: itemCount,
+            itemBuilder: (BuildContext context, int index) {
+              return SizedBox(
+                height: itemHeight,
+                child: Text('Tile $index'),
+              );
+            },
+          ),
+        ),
+      );
+
+      expect(semantics, includesNodeWith(actions: <SemanticsAction>[SemanticsAction.scrollLeft]));
+
+      // Jump to the end.
+      controller.jumpTo(itemCount * itemHeight);
+      await tester.pumpAndSettle();
+      expect(semantics, includesNodeWith(actions: <SemanticsAction>[SemanticsAction.scrollRight]));
+
+      semantics.dispose();
+    });
+
+    testWidgets('reverse horizontal', (WidgetTester tester) async {
+      final SemanticsTester semantics = SemanticsTester(tester);
+      final ScrollController controller = ScrollController();
+
+      await tester.pumpWidget(
+        Directionality(
+          textDirection: TextDirection.ltr,
+          child: ListView.builder(
+            scrollDirection: Axis.horizontal,
+            reverse: true,
+            controller: controller,
+            itemCount: itemCount,
+            itemBuilder: (BuildContext context, int index) {
+              return SizedBox(
+                height: itemHeight,
+                child: Text('Tile $index'),
+              );
+            },
+          ),
+        ),
+      );
+
+      expect(semantics, includesNodeWith(actions: <SemanticsAction>[SemanticsAction.scrollRight]));
+
+      // Jump to the end.
+      controller.jumpTo(itemCount * itemHeight);
+      await tester.pumpAndSettle();
+      expect(semantics, includesNodeWith(actions: <SemanticsAction>[SemanticsAction.scrollLeft]));
+
+      semantics.dispose();
+    });
+  });
+}