From ce2fe59bbb7ecbc820069724da834b373c0223c3 Mon Sep 17 00:00:00 2001
From: PurplePolyhedron <120297255+PurplePolyhedron@users.noreply.github.com>
Date: Wed, 2 Oct 2024 13:46:23 +0800
Subject: [PATCH] fix `DropdownMenu` keyboard navigation when entries are
 filtered empty (#155252)

fixes https://github.com/flutter/flutter/issues/154532
---
 .../lib/src/material/dropdown_menu.dart       |  1 +
 .../test/material/dropdown_menu_test.dart     | 22 +++++++++++++++++++
 2 files changed, 23 insertions(+)

diff --git a/packages/flutter/lib/src/material/dropdown_menu.dart b/packages/flutter/lib/src/material/dropdown_menu.dart
index 2539dd6ef6..7050a4e161 100644
--- a/packages/flutter/lib/src/material/dropdown_menu.dart
+++ b/packages/flutter/lib/src/material/dropdown_menu.dart
@@ -807,6 +807,7 @@ class _DropdownMenuState<T> extends State<DropdownMenu<T>> {
     } else {
       filteredEntries = widget.dropdownMenuEntries;
     }
+    _menuHasEnabledItem = filteredEntries.any((DropdownMenuEntry<T> entry) => entry.enabled);
 
     if (_enableSearch) {
       if (widget.searchCallback != null) {
diff --git a/packages/flutter/test/material/dropdown_menu_test.dart b/packages/flutter/test/material/dropdown_menu_test.dart
index 795be7eb21..f394799360 100644
--- a/packages/flutter/test/material/dropdown_menu_test.dart
+++ b/packages/flutter/test/material/dropdown_menu_test.dart
@@ -1315,6 +1315,28 @@ void main() {
     expect(tester.takeException(), isNull);
   });
 
+  // Regression test for https://github.com/flutter/flutter/issues/154532.
+  testWidgets('Searching for non matching item does not crash', (WidgetTester tester) async {
+    await tester.pumpWidget(MaterialApp(
+      home: Scaffold(
+        body: DropdownMenu<TestMenu>(
+          enableFilter: true,
+          requestFocusOnTap: true,
+          dropdownMenuEntries: menuChildren,
+        ),
+      ),
+    ));
+
+    // Open the menu.
+    await tester.tap(find.byType(DropdownMenu<TestMenu>));
+    await tester.pump();
+    await tester.enterText(find.byType(TextField).first, 'Me');
+    await tester.pumpAndSettle();
+    await tester.enterText(find.byType(TextField).first, 'Meu');
+    await tester.pumpAndSettle();
+    expect(tester.takeException(), isNull);
+  });
+
   // Regression test for https://github.com/flutter/flutter/issues/147253.
   testWidgets('Default search prioritises the current highlight on desktop platforms',
       (WidgetTester tester) async {