Reland: Request focus if accessibility focus is given to a Focus widg…

…et (#142942) (#149840)

## Description

This attempts to re-land #142942 after being reverted in flutter/flutter#149741 because it broke the iOS [platform view UI integration test](https://github.com/flutter/flutter/blob/master/dev/integration_tests/ios_platform_view_tests/ios/PlatformViewUITests/PlatformViewUITests.m?rgh-link-date=2024-06-06T19%3A47%3A27Z).

The changes here from the original are that in the Focus widget we no longer set the `onFocus` for the `Semantics` if the platform is iOS.  It was not intended to do anything on iOS anyhow.

Also, I updated the matchers to not actually do anything yet with the SemanticsAction.focus matching, so that this can be landed without breaking customer tests, and once they have been updated to correctly look for the focus action, we can land a PR that will turn it on.

## Related Issues
 - flutter/flutter#149838
 - flutter/flutter#83809
 - flutter/flutter#149842

## Tests
 - Updated framework tests to look for the appropriate things using the matchers, even though it doesn't actually test for them yet.

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 +671,15 @@ 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.
+        // TODO(gspencergoog): Allow this to be set on iOS once the issue is
+        // addressed: https://github.com/flutter/flutter/issues/150030
+        onFocus: defaultTargetPlatform != TargetPlatform.iOS && _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

@@ -148,6 +148,7 @@ void main() {
         ],
         actions: <SemanticsAction>[
           SemanticsAction.tap,
+          SemanticsAction.focus,
         ],
       ),
     );
@@ -172,6 +173,7 @@ void main() {
       hasEnabledState: true,
       isEnabled: true,
       hasTapAction: true,
+      hasFocusAction: true,
       isFocusable: true,
       isInMutuallyExclusiveGroup: true,
     ));
@@ -191,6 +193,7 @@ void main() {
       hasEnabledState: true,
       isEnabled: true,
       hasTapAction: true,
+      hasFocusAction: true,
       isFocusable: true,
       isInMutuallyExclusiveGroup: true,
       isChecked: true,
@@ -211,6 +214,7 @@ 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,
                             ),