Add:创建 flutter go web 版

packages/flutter_web/test/widgets/test_widgets.dart

@@ -0,0 +1,61 @@
+// Copyright 2015 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/rendering.dart';
+import 'package:flutter_web/widgets.dart';
+
+const BoxDecoration kBoxDecorationA = const BoxDecoration(
+  color: const Color(0xFFFF0000),
+);
+
+const BoxDecoration kBoxDecorationB = const BoxDecoration(
+  color: const Color(0xFF00FF00),
+);
+
+const BoxDecoration kBoxDecorationC = const BoxDecoration(
+  color: const Color(0xFF0000FF),
+);
+
+class TestBuildCounter extends StatelessWidget {
+  static int buildCount = 0;
+
+  @override
+  Widget build(BuildContext context) {
+    buildCount += 1;
+    return const DecoratedBox(decoration: kBoxDecorationA);
+  }
+}
+
+class FlipWidget extends StatefulWidget {
+  const FlipWidget({Key key, this.left, this.right}) : super(key: key);
+
+  final Widget left;
+  final Widget right;
+
+  @override
+  FlipWidgetState createState() => new FlipWidgetState();
+}
+
+class FlipWidgetState extends State<FlipWidget> {
+  bool _showLeft = true;
+
+  void flip() {
+    setState(() {
+      _showLeft = !_showLeft;
+    });
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return _showLeft ? widget.left : widget.right;
+  }
+}
+
+void flipStatefulWidget(WidgetTester tester, {bool skipOffstage = true}) {
+  tester
+      .state<FlipWidgetState>(
+          find.byType(FlipWidget, skipOffstage: skipOffstage))
+      .flip();
+}