Request focus if SemanticsAction.focus is sent to a focusable widge…

…t (#142942)

## Description

This causes the `Focus` widget to request focus on its focus node if the accessibility system (screen reader) focuses a widget via the `SemanticsAction.focus` action.

## Related Issues
 - flutter/flutter#83809

## Tests
 - Added a test to make sure that focus is requested when `SemanticsAction.focus` is sent by the engine.

dev/integration_tests/flutter_gallery/test/demo/material/chip_demo_test.dart

@@ -20,6 +20,7 @@ void main() {
       isEnabled: true,
       isFocusable: true,
       hasTapAction: true,
+      hasFocusAction: true,
       label: 'Update border shape',
     ));
 
@@ -29,6 +30,7 @@ void main() {
       isEnabled: true,
       isFocusable: true,
       hasTapAction: true,
+      hasFocusAction: true,
       label: 'Reset chips',
     ));
 

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

@@ -671,6 +671,14 @@ class _FocusState extends State<Focus> {
     Widget child = widget.child;
     if (widget.includeSemantics) {
       child = Semantics(
+        // Automatically request the focus for a focusable widget when it
+        // receives an input focus action from the semantics. Nothing is needed
+        // for losing the focus because if focus is lost, that means another
+        // node will gain focus and take focus from this widget.
+        onFocus:
+          _couldRequestFocus
+          ? focusNode.requestFocus
+          : null,
         focusable: _couldRequestFocus,
         focused: _hadPrimaryFocus,
         child: widget.child,

packages/flutter/test/cupertino/checkbox_test.dart

@@ -34,6 +34,7 @@ void main() {
       hasEnabledState: true,
       isEnabled: true,
       hasTapAction: true,
+      hasFocusAction: true,
       isFocusable: true,
     ));
 
@@ -54,6 +55,7 @@ void main() {
       isChecked: true,
       isEnabled: true,
       hasTapAction: true,
+      hasFocusAction: true,
       isFocusable: true,
     ));
 
@@ -73,6 +75,7 @@ void main() {
       hasEnabledState: true,
       // isFocusable is delayed by 1 frame.
       isFocusable: true,
+      hasFocusAction: true,
     ));
 
     await tester.pump();
@@ -178,6 +181,7 @@ void main() {
       hasEnabledState: true,
       isEnabled: true,
       hasTapAction: true,
+      hasFocusAction: true,
       isFocusable: true,
     ));
     handle.dispose();
@@ -247,7 +251,7 @@ void main() {
         SemanticsFlag.isFocusable,
         SemanticsFlag.isCheckStateMixed,
       ],
-      actions: <SemanticsAction>[SemanticsAction.tap],
+      actions: <SemanticsAction>[SemanticsAction.tap, SemanticsAction.focus],
     ), hasLength(1));
 
     await tester.pumpWidget(
@@ -268,7 +272,7 @@ void main() {
         SemanticsFlag.isChecked,
         SemanticsFlag.isFocusable,
       ],
-      actions: <SemanticsAction>[SemanticsAction.tap],
+      actions: <SemanticsAction>[SemanticsAction.tap, SemanticsAction.focus],
     ), hasLength(1));
 
     await tester.pumpWidget(
@@ -288,7 +292,7 @@ void main() {
         SemanticsFlag.isEnabled,
         SemanticsFlag.isFocusable,
       ],
-      actions: <SemanticsAction>[SemanticsAction.tap],
+      actions: <SemanticsAction>[SemanticsAction.tap, SemanticsAction.focus],
     ), hasLength(1));
 
     semantics.dispose();

packages/flutter/test/cupertino/radio_test.dart

@@ -147,6 +147,7 @@ void main() {
         ],
         actions: <SemanticsAction>[
           SemanticsAction.tap,
+          SemanticsAction.focus,
         ],
       ),
     );
@@ -171,6 +172,7 @@ void main() {
       hasEnabledState: true,
       isEnabled: true,
       hasTapAction: true,
+      hasFocusAction: true,
       isFocusable: true,
       isInMutuallyExclusiveGroup: true,
     ));
@@ -190,6 +192,7 @@ void main() {
       hasEnabledState: true,
       isEnabled: true,
       hasTapAction: true,
+      hasFocusAction: true,
       isFocusable: true,
       isInMutuallyExclusiveGroup: true,
       isChecked: true,
@@ -210,6 +213,7 @@ void main() {
       hasEnabledState: true,
       isFocusable: true,
       isInMutuallyExclusiveGroup: true,
+      hasFocusAction: true,
     ));
 
     await tester.pump();

packages/flutter/test/cupertino/route_test.dart

@@ -1945,7 +1945,7 @@ void main() {
     await tester.pumpAndSettle();
 
     expect(semantics, isNot(includesNodeWith(
-      actions: <SemanticsAction>[SemanticsAction.tap],
+      actions: <SemanticsAction>[SemanticsAction.tap, SemanticsAction.focus],
       label: 'Dismiss',
     )));
     debugDefaultTargetPlatformOverride = null;

packages/flutter/test/cupertino/text_field_test.dart

@@ -2621,7 +2621,7 @@ void main() {
       ),
     );
 
-    expect(semantics, isNot(includesNodeWith(actions: <SemanticsAction>[SemanticsAction.tap])));
+    expect(semantics, isNot(includesNodeWith(actions: <SemanticsAction>[SemanticsAction.tap, SemanticsAction.focus])));
 
     semantics.dispose();
   });

packages/flutter/test/material/back_button_test.dart

@@ -215,6 +215,7 @@ void main() {
       hasEnabledState: true,
       isEnabled: true,
       hasTapAction: true,
+      hasFocusAction: true,
       isFocusable: true,
     ));
     handle.dispose();
@@ -258,6 +259,7 @@ void main() {
       hasEnabledState: true,
       isEnabled: true,
       hasTapAction: true,
+      hasFocusAction: true,
       isFocusable: true,
     ));
     handle.dispose();

packages/flutter/test/material/bottom_navigation_bar_test.dart

@@ -2111,6 +2111,7 @@ void main() {
         isFocusable: true,
         isSelected: true,
         hasTapAction: true,
+        hasFocusAction: true,
       ),
     );
     expect(
@@ -2120,6 +2121,7 @@ void main() {
         textDirection: TextDirection.ltr,
         isFocusable: true,
         hasTapAction: true,
+        hasFocusAction: true,
       ),
     );
     expect(
@@ -2129,6 +2131,7 @@ void main() {
         textDirection: TextDirection.ltr,
         isFocusable: true,
         hasTapAction: true,
+        hasFocusAction: true,
       ),
     );
   });
@@ -2165,6 +2168,7 @@ void main() {
         isFocusable: true,
         isSelected: true,
         hasTapAction: true,
+        hasFocusAction: true,
       ),
     );
     expect(
@@ -2174,6 +2178,7 @@ void main() {
         textDirection: TextDirection.ltr,
         isFocusable: true,
         hasTapAction: true,
+        hasFocusAction: true,
       ),
     );
     expect(
@@ -2183,6 +2188,7 @@ void main() {
         textDirection: TextDirection.ltr,
         isFocusable: true,
         hasTapAction: true,
+        hasFocusAction: true,
       ),
     );
   });
@@ -2515,6 +2521,7 @@ void main() {
         isFocusable: true,
         isSelected: true,
         hasTapAction: true,
+        hasFocusAction: true,
       ),
     );
     expect(
@@ -2524,6 +2531,7 @@ void main() {
         textDirection: TextDirection.ltr,
         isFocusable: true,
         hasTapAction: true,
+        hasFocusAction: true,
       ),
     );
   });
@@ -2558,6 +2566,7 @@ void main() {
         isFocusable: true,
         isSelected: true,
         hasTapAction: true,
+        hasFocusAction: true,
       ),
     );
     expect(
@@ -2567,6 +2576,7 @@ void main() {
         textDirection: TextDirection.ltr,
         isFocusable: true,
         hasTapAction: true,
+        hasFocusAction: true,
       ),
     );
   });
@@ -2747,13 +2757,13 @@ void main() {
                                 SemanticsFlag.isSelected,
                                 SemanticsFlag.isFocusable,
                               ],
-                              actions: <SemanticsAction>[SemanticsAction.tap],
+                              actions: <SemanticsAction>[SemanticsAction.tap, SemanticsAction.focus],
                               label: 'A\nTab 1 of 2',
                               textDirection: TextDirection.ltr,
                             ),
                             TestSemantics(
                               flags: <SemanticsFlag>[SemanticsFlag.isFocusable],
-                              actions: <SemanticsAction>[SemanticsAction.tap],
+                              actions: <SemanticsAction>[SemanticsAction.tap, SemanticsAction.focus],
                               label: 'B\nTab 2 of 2',
                               textDirection: TextDirection.ltr,
                             ),