Add test for undo_history_controller.0.dart (flutter#148205)

Contributes to flutter#130459

It adds test for `examples/api/test/widgets/undo_history/undo_history_controller.0_test.dart`.

Author: ValentinVignal

dev/bots/check_code_samples.dart

@@ -420,7 +420,6 @@ final Set<String> _knownMissingTests = <String>{
   'examples/api/test/widgets/notification_listener/notification.0_test.dart',
   'examples/api/test/widgets/editable_text/text_editing_controller.0_test.dart',
   'examples/api/test/widgets/editable_text/editable_text.on_changed.0_test.dart',
-  'examples/api/test/widgets/undo_history/undo_history_controller.0_test.dart',
   'examples/api/test/widgets/overscroll_indicator/glowing_overscroll_indicator.1_test.dart',
   'examples/api/test/widgets/overscroll_indicator/glowing_overscroll_indicator.0_test.dart',
   'examples/api/test/widgets/tween_animation_builder/tween_animation_builder.0_test.dart',

examples/api/test/widgets/undo_history/undo_history_controller.0_test.dart

@@ -0,0 +1,50 @@
+// Copyright 2014 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:flutter/material.dart';
+import 'package:flutter_api_samples/widgets/undo_history/undo_history_controller.0.dart' as example;
+import 'package:flutter_test/flutter_test.dart';
+
+void main() {
+  testWidgets('The undo history controller should undo and redo the history changes', (WidgetTester tester) async {
+    await tester.pumpWidget(
+      const example.UndoHistoryControllerExampleApp(),
+    );
+
+    // Equals to UndoHistoryState._kThrottleDuration.
+    const Duration kThrottleDuration = Duration(milliseconds: 500);
+
+    expect(find.byType(TextField), findsOne);
+    expect(find.widgetWithText(TextButton, 'Undo'), findsOne);
+    expect(find.widgetWithText(TextButton, 'Redo'), findsOne);
+
+    await tester.enterText(find.byType(TextField), '1st change');
+    await tester.pump(kThrottleDuration);
+    expect(find.text('1st change'), findsOne);
+
+    await tester.enterText(find.byType(TextField), '2nd change');
+    await tester.pump(kThrottleDuration);
+    expect(find.text('2nd change'), findsOne);
+
+    await tester.enterText(find.byType(TextField), '3rd change');
+    await tester.pump(kThrottleDuration);
+    expect(find.text('3rd change'), findsOne);
+
+    await tester.tap(find.text('Undo'));
+    await tester.pump();
+    expect(find.text('2nd change'), findsOne);
+
+    await tester.tap(find.text('Undo'));
+    await tester.pump();
+    expect(find.text('1st change'), findsOne);
+
+    await tester.tap(find.text('Redo'));
+    await tester.pump();
+    expect(find.text('2nd change'), findsOne);
+
+    await tester.tap(find.text('Redo'));
+    await tester.pump();
+    expect(find.text('3rd change'), findsOne);
+  });
+}