[VPAT][A11y] Announce Autocomplete search results status (flutter#173480)

Status announcements 'Search results found' and 'no results found' were
observed on a search view on the iOS sheets app.

Fixes [[VPAT][A11y] autocomplete must announce status when search result
is available](flutter#173064)
Fixes b/429094918

Author: victorsanni

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

@@ -19,6 +19,8 @@ import 'editable_text.dart';
 import 'focus_manager.dart';
 import 'framework.dart';
 import 'inherited_notifier.dart';
+import 'localizations.dart';
+import 'media_query.dart';
 import 'overlay.dart';
 import 'shortcuts.dart';
 import 'tap_region.dart';
@@ -404,6 +406,17 @@ class _RawAutocompleteState<T extends Object> extends State<RawAutocomplete<T>>
     }
   }
 
+  void _announceSemantics(bool resultsAvailable) {
+    if (!MediaQuery.supportsAnnounceOf(context)) {
+      return;
+    }
+    final WidgetsLocalizations localizations = WidgetsLocalizations.of(context);
+    final String optionsHint = resultsAvailable
+        ? localizations.searchResultsFound
+        : localizations.noResultsFound;
+    SemanticsService.announce(optionsHint, localizations.textDirection);
+  }
+
   // Assigning an ID to every call of _onChangedField is necessary to avoid a
   // situation where _options is updated by an older call when multiple
   // _onChangedField calls are running simultaneously.
@@ -426,6 +439,9 @@ class _RawAutocompleteState<T extends Object> extends State<RawAutocomplete<T>>
     if (callId != _onChangedCallId || !shouldUpdateOptions) {
       return;
     }
+    if (_options.isEmpty != options.isEmpty) {
+      _announceSemantics(options.isNotEmpty);
+    }
     _options = options;
     _updateHighlight(_highlightedOptionIndex.value);
     final T? selection = _selection;

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

@@ -194,6 +194,14 @@ abstract class WidgetsLocalizations {
   /// list one space right in the list.
   String get reorderItemRight;
 
+  /// The semantics label used for [RawAutocomplete] when the options list goes
+  /// from empty to non-empty.
+  String get searchResultsFound => 'Search results found';
+
+  /// The semantics label used for [RawAutocomplete] when the options list goes
+  /// from non-empty to empty.
+  String get noResultsFound => 'No results found';
+
   /// Label for "copy" edit buttons and menu items.
   String get copyButtonLabel;
 
@@ -284,6 +292,12 @@ class DefaultWidgetsLocalizations implements WidgetsLocalizations {
   @override
   String get reorderItemToStart => 'Move to the start';
 
+  @override
+  String get searchResultsFound => 'Search results found';
+
+  @override
+  String get noResultsFound => 'No results found';
+
   @override
   String get copyButtonLabel => 'Copy';
 

packages/flutter/test/widgets/autocomplete_test.dart

@@ -3271,6 +3271,78 @@ void main() {
     expect(find.byKey(optionsKey), findsOneWidget);
   });
 
+  testWidgets('Autocomplete Semantics announcement', (WidgetTester tester) async {
+    final SemanticsHandle handle = tester.ensureSemantics();
+    final GlobalKey fieldKey = GlobalKey();
+    final GlobalKey optionsKey = GlobalKey();
+    late Iterable<String> lastOptions;
+    late FocusNode focusNode;
+    late TextEditingController textEditingController;
+    const DefaultWidgetsLocalizations localizations = DefaultWidgetsLocalizations();
+
+    await tester.pumpWidget(
+      MaterialApp(
+        home: Scaffold(
+          body: RawAutocomplete<String>(
+            optionsBuilder: (TextEditingValue textEditingValue) {
+              return kOptions.where((String option) {
+                return option.contains(textEditingValue.text.toLowerCase());
+              });
+            },
+            fieldViewBuilder:
+                (
+                  BuildContext context,
+                  TextEditingController fieldTextEditingController,
+                  FocusNode fieldFocusNode,
+                  VoidCallback onFieldSubmitted,
+                ) {
+                  focusNode = fieldFocusNode;
+                  textEditingController = fieldTextEditingController;
+                  return TextField(
+                    key: fieldKey,
+                    focusNode: focusNode,
+                    controller: textEditingController,
+                  );
+                },
+            optionsViewBuilder:
+                (
+                  BuildContext context,
+                  AutocompleteOnSelected<String> onSelected,
+                  Iterable<String> options,
+                ) {
+                  lastOptions = options;
+                  return Container(key: optionsKey);
+                },
+          ),
+        ),
+      ),
+    );
+
+    expect(find.byKey(fieldKey), findsOneWidget);
+    expect(find.byKey(optionsKey), findsNothing);
+
+    expect(tester.takeAnnouncements(), isEmpty);
+
+    focusNode.requestFocus();
+    await tester.pump();
+    expect(find.byKey(optionsKey), findsOneWidget);
+    expect(lastOptions.length, kOptions.length);
+    expect(tester.takeAnnouncements().first.message, localizations.searchResultsFound);
+
+    await tester.enterText(find.byKey(fieldKey), 'a');
+    await tester.pump();
+    expect(find.byKey(optionsKey), findsOneWidget);
+    expect(lastOptions.length, greaterThan(0));
+    expect(tester.takeAnnouncements(), isEmpty);
+
+    await tester.enterText(find.byKey(fieldKey), 'zzzz');
+    await tester.pump();
+    expect(find.byKey(optionsKey), findsNothing);
+    expect(tester.takeAnnouncements().first.message, localizations.noResultsFound);
+
+    handle.dispose();
+  });
+
   testWidgets('RawAutocomplete renders at zero area', (WidgetTester tester) async {
     await tester.pumpWidget(
       MaterialApp(

packages/flutter/test/widgets/localizations_test.dart

@@ -22,6 +22,8 @@ void main() {
     expect(localizations.reorderItemRight, isNotNull);
     expect(localizations.reorderItemToEnd, isNotNull);
     expect(localizations.reorderItemToStart, isNotNull);
+    expect(localizations.searchResultsFound, isNotNull);
+    expect(localizations.noResultsFound, isNotNull);
     expect(localizations.copyButtonLabel, isNotNull);
     expect(localizations.cutButtonLabel, isNotNull);
     expect(localizations.pasteButtonLabel, isNotNull);