a11y: handle left/right scrolls correctly (#11309)

* a11y: handle left/right scrolls correctly

* fix keep alive test

* fix scaffold test

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

@@ -267,6 +267,7 @@ class DrawerControllerState extends State<DrawerController> with SingleTickerPro
         onHorizontalDragUpdate: _move,
         onHorizontalDragEnd: _settle,
         onHorizontalDragCancel: _handleDragCancel,
+        excludeFromSemantics: true,
         child: new RepaintBoundary(
           child: new Stack(
             children: <Widget>[

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

@@ -728,7 +728,7 @@ class _GestureSemantics extends SingleChildRenderObjectWidget {
     renderObject
       ..onTap = recognizers.containsKey(TapGestureRecognizer) ? _handleTap : null
       ..onLongPress = recognizers.containsKey(LongPressGestureRecognizer) ? _handleLongPress : null
-      ..onHorizontalDragUpdate = recognizers.containsKey(VerticalDragGestureRecognizer) ||
+      ..onHorizontalDragUpdate = recognizers.containsKey(HorizontalDragGestureRecognizer) ||
           recognizers.containsKey(PanGestureRecognizer) ? _handleHorizontalDragUpdate : null
       ..onVerticalDragUpdate = recognizers.containsKey(VerticalDragGestureRecognizer) ||
           recognizers.containsKey(PanGestureRecognizer) ? _handleVerticalDragUpdate : null;

packages/flutter/test/widgets/gesture_detector_semantics_test.dart

+// Copyright 2017 The Chromium 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/rendering.dart';
+import 'package:flutter/widgets.dart';
+
+import 'semantics_tester.dart';
+
+void main() {
+  testWidgets('Vertical gesture detector has up/down actions', (WidgetTester tester) async {
+    final SemanticsTester semantics = new SemanticsTester(tester);
+
+    int callCount = 0;
+    final GlobalKey detectorKey = new GlobalKey();
+
+    await tester.pumpWidget(
+      new Center(
+        child: new GestureDetector(
+          key: detectorKey,
+          onVerticalDragStart: (DragStartDetails _) {
+            callCount += 1;
+          },
+          child: new Container(),
+        ),
+      )
+    );
+
+    expect(semantics, includesNodeWith(
+        actions: <SemanticsAction>[SemanticsAction.scrollUp, SemanticsAction.scrollDown])
+    );
+
+    final int detectorId = detectorKey.currentContext.findRenderObject().debugSemantics.id;
+    tester.binding.pipelineOwner.semanticsOwner.performAction(detectorId, SemanticsAction.scrollLeft);
+    tester.binding.pipelineOwner.semanticsOwner.performAction(detectorId, SemanticsAction.scrollRight);
+    expect(callCount, 0);
+    tester.binding.pipelineOwner.semanticsOwner.performAction(detectorId, SemanticsAction.scrollUp);
+    expect(callCount, 1);
+    tester.binding.pipelineOwner.semanticsOwner.performAction(detectorId, SemanticsAction.scrollDown);
+    expect(callCount, 2);
+  });
+
+  testWidgets('Horizontal gesture detector has up/down actions', (WidgetTester tester) async {
+    final SemanticsTester semantics = new SemanticsTester(tester);
+
+    int callCount = 0;
+    final GlobalKey detectorKey = new GlobalKey();
+
+    await tester.pumpWidget(
+        new Center(
+          child: new GestureDetector(
+            key: detectorKey,
+            onHorizontalDragStart: (DragStartDetails _) {
+              callCount += 1;
+            },
+            child: new Container(),
+          ),
+        )
+    );
+
+    expect(semantics, includesNodeWith(
+        actions: <SemanticsAction>[SemanticsAction.scrollLeft, SemanticsAction.scrollRight])
+    );
+
+    final int detectorId = detectorKey.currentContext.findRenderObject().debugSemantics.id;
+    tester.binding.pipelineOwner.semanticsOwner.performAction(detectorId, SemanticsAction.scrollUp);
+    tester.binding.pipelineOwner.semanticsOwner.performAction(detectorId, SemanticsAction.scrollDown);
+    expect(callCount, 0);
+    tester.binding.pipelineOwner.semanticsOwner.performAction(detectorId, SemanticsAction.scrollLeft);
+    expect(callCount, 1);
+    tester.binding.pipelineOwner.semanticsOwner.performAction(detectorId, SemanticsAction.scrollRight);
+    expect(callCount, 2);
+  });
+}

packages/flutter/test/widgets/keep_alive_test.dart

@@ -219,7 +219,7 @@ void main() {
       '         │ constraints: BoxConstraints(w=800.0, h=600.0)\n'
       '         │ semantic boundary\n'
       '         │ size: Size(800.0, 600.0)\n'
-      '         │ gestures: horizontal scroll, vertical scroll\n'
+      '         │ gestures: vertical scroll\n'
       '         │\n'
       '         └─child: RenderPointerListener#00000\n'
       '           │ creator: Listener ← _GestureSemantics ←\n'
@@ -389,7 +389,7 @@ void main() {
       '         │ constraints: BoxConstraints(w=800.0, h=600.0)\n'
       '         │ semantic boundary\n'
       '         │ size: Size(800.0, 600.0)\n'
-      '         │ gestures: horizontal scroll, vertical scroll\n'
+      '         │ gestures: vertical scroll\n'
       '         │\n'
       '         └─child: RenderPointerListener#00000\n'
       '           │ creator: Listener ← _GestureSemantics ←\n'