Add:创建 flutter go web 版

packages/flutter_web/test/widgets/unique_widget_test.dart

@@ -0,0 +1,36 @@
+// Copyright 2016 The Chromium 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_web_test/flutter_web_test.dart';
+import 'package:flutter_web/widgets.dart';
+
+class TestUniqueWidget extends UniqueWidget<TestUniqueWidgetState> {
+  const TestUniqueWidget({GlobalKey<TestUniqueWidgetState> key})
+      : super(key: key);
+
+  @override
+  TestUniqueWidgetState createState() => TestUniqueWidgetState();
+}
+
+class TestUniqueWidgetState extends State<TestUniqueWidget> {
+  @override
+  Widget build(BuildContext context) => Container();
+}
+
+void main() {
+  testWidgets('Unique widget control test', (WidgetTester tester) async {
+    final TestUniqueWidget widget =
+        TestUniqueWidget(key: GlobalKey<TestUniqueWidgetState>());
+
+    await tester.pumpWidget(widget);
+
+    final TestUniqueWidgetState state = widget.currentState;
+
+    expect(state, isNotNull);
+
+    await tester.pumpWidget(Container(child: widget));
+
+    expect(widget.currentState, equals(state));
+  });
+}