Add InputDatePickerFormField.focusNode prop (flutter#136673)

Adds `focusNode` prop to `InputDatePickerFormField` widget.

Fixes flutter#105881

Author: piedcipher

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

@@ -57,6 +57,7 @@ class InputDatePickerFormField extends StatefulWidget {
     this.keyboardType,
     this.autofocus = false,
     this.acceptEmptyDate = false,
+    this.focusNode,
   }) : initialDate = initialDate != null ? DateUtils.dateOnly(initialDate) : null,
        firstDate = DateUtils.dateOnly(firstDate),
        lastDate = DateUtils.dateOnly(lastDate) {
@@ -136,6 +137,9 @@ class InputDatePickerFormField extends StatefulWidget {
   /// If true, [errorFormatText] is not shown when the date input field is empty.
   final bool acceptEmptyDate;
 
+  /// {@macro flutter.widgets.Focus.focusNode}
+  final FocusNode? focusNode;
+
   @override
   State<InputDatePickerFormField> createState() => _InputDatePickerFormFieldState();
 }
@@ -266,6 +270,7 @@ class _InputDatePickerFormFieldState extends State<InputDatePickerFormField> {
       onFieldSubmitted: _handleSubmitted,
       autofocus: widget.autofocus,
       controller: _controller,
+      focusNode: widget.focusNode,
     );
   }
 }

packages/flutter/test/material/input_date_picker_form_field_test.dart

@@ -51,6 +51,7 @@ void main() {
     ThemeData? theme,
     Iterable<LocalizationsDelegate<dynamic>>? localizationsDelegates,
     bool acceptEmptyDate = false,
+    FocusNode? focusNode,
   }) {
     return MaterialApp(
       theme: theme ?? ThemeData.from(colorScheme: const ColorScheme.light()),
@@ -72,6 +73,7 @@ void main() {
             fieldLabelText: fieldLabelText,
             autofocus: autofocus,
             acceptEmptyDate: acceptEmptyDate,
+            focusNode: focusNode,
           ),
         ),
       ),
@@ -378,4 +380,19 @@ void main() {
       expect(find.text(errorFormatText), findsOneWidget);
     });
   });
+
+  testWidgets('FocusNode can request focus', (WidgetTester tester) async {
+    final FocusNode focusNode = FocusNode();
+    await tester.pumpWidget(inputDatePickerField(
+      focusNode: focusNode,
+    ));
+    expect((tester.widget(find.byType(TextField)) as TextField).focusNode, focusNode);
+    expect(focusNode.hasFocus, isFalse);
+    focusNode.requestFocus();
+    await tester.pumpAndSettle();
+    expect(focusNode.hasFocus, isTrue);
+    focusNode.unfocus();
+    await tester.pumpAndSettle();
+    expect(focusNode.hasFocus, isFalse);
+  });
 }