added autofocus and test (#87591)

packages/flutter/lib/src/cupertino/search_field.dart

@@ -151,6 +151,7 @@ class CupertinoSearchTextField extends StatefulWidget {
     this.onSuffixTap,
     this.restorationId,
     this.focusNode,
+    this.autofocus = false,
     this.onTap,
     this.autocorrect = true,
     this.enabled,
@@ -287,6 +288,9 @@ class CupertinoSearchTextField extends StatefulWidget {
   /// {@macro flutter.widgets.Focus.focusNode}
   final FocusNode? focusNode;
 
+  /// {@macro flutter.widgets.editableText.autofocus}
+  final bool autofocus;
+
   /// {@macro flutter.material.textfield.onTap}
   final VoidCallback? onTap;
 
@@ -429,6 +433,7 @@ class _CupertinoSearchTextFieldState extends State<CupertinoSearchTextField>
       onChanged: widget.onChanged,
       onSubmitted: widget.onSubmitted,
       focusNode: widget.focusNode,
+      autofocus: widget.autofocus,
       autocorrect: widget.autocorrect,
       textInputAction: TextInputAction.search,
     );

packages/flutter/test/cupertino/search_field_test.dart

@@ -562,4 +562,20 @@ void main() {
     final CupertinoTextField textField = tester.widget(find.byType(CupertinoTextField));
     expect(textField.textInputAction, TextInputAction.search);
   });
+
+  testWidgets('autofocus:true gives focus to the widget', (WidgetTester tester) async {
+    final FocusNode focusNode = FocusNode();
+    await tester.pumpWidget(
+      CupertinoApp(
+        home: Center(
+          child: CupertinoSearchTextField(
+            focusNode: focusNode,
+            autofocus: true,
+          ),
+        ),
+      ),
+    );
+
+    expect(focusNode.hasFocus, isTrue);
+  });
 }