allow changing textAlign of TextField in DropdownMenu (#148074)

PR for #147991

Author: angelocordero

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

@@ -154,6 +154,7 @@ class DropdownMenu<T> extends StatefulWidget {
     this.enableFilter = false,
     this.enableSearch = true,
     this.textStyle,
+    this.textAlign = TextAlign.start,
     this.inputDecorationTheme,
     this.menuStyle,
     this.controller,
@@ -264,6 +265,11 @@ class DropdownMenu<T> extends StatefulWidget {
   /// if the dropdown menu theme's value is null.
   final TextStyle? textStyle;
 
+  /// The text align for the [TextField] of the [DropdownMenu].
+  ///
+  /// Defaults to [TextAlign.start].
+  final TextAlign textAlign;
+
   /// Defines the default appearance of [InputDecoration] to show around the text field.
   ///
   /// By default, shows a outlined text field.
@@ -754,6 +760,7 @@ class _DropdownMenuState<T> extends State<DropdownMenu<T>> {
           focusNode: widget.focusNode,
           canRequestFocus: canRequestFocus(),
           enableInteractiveSelection: canRequestFocus(),
+          textAlign: widget.textAlign,
           textAlignVertical: TextAlignVertical.center,
           style: effectiveTextStyle,
           controller: _localTextEditingController,

packages/flutter/test/material/dropdown_menu_test.dart

@@ -2293,6 +2293,29 @@ void main() {
     // One is layout for the _DropdownMenuBody, the other one is the real button item in the menu.
     expect(find.widgetWithText(MenuItemButton, labelText), findsNWidgets(2));
   });
+
+  testWidgets('DropdownMenu allows customizing text field text align', (WidgetTester tester) async {
+    await tester.pumpWidget(const MaterialApp(
+      home: Scaffold(
+        body: Column(
+          children: <DropdownMenu<int>>[
+            DropdownMenu<int>(
+              dropdownMenuEntries: <DropdownMenuEntry<int>>[],
+            ),
+             DropdownMenu<int>(
+              textAlign: TextAlign.center,
+              dropdownMenuEntries: <DropdownMenuEntry<int>>[],
+            ),
+          ],
+        ),
+      ),
+    ));
+
+    final List<TextField> fields = tester.widgetList<TextField>(find.byType(TextField)).toList();
+
+    expect(fields[0].textAlign, TextAlign.start);
+    expect(fields[1].textAlign, TextAlign.center);
+  });
 }
 
 enum TestMenu {