Add:创建 flutter go web 版

packages/flutter_web/test/widgets/scrollable_of_test.dart

@@ -0,0 +1,92 @@
+// 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 ScrollPositionListener extends StatefulWidget {
+  const ScrollPositionListener({Key key, this.child, this.log})
+      : super(key: key);
+
+  final Widget child;
+  final ValueChanged<String> log;
+
+  @override
+  _ScrollPositionListenerState createState() =>
+      new _ScrollPositionListenerState();
+}
+
+class _ScrollPositionListenerState extends State<ScrollPositionListener> {
+  ScrollPosition _position;
+
+  @override
+  void didChangeDependencies() {
+    super.didChangeDependencies();
+    _position?.removeListener(listener);
+    _position = Scrollable.of(context)?.position;
+    _position?.addListener(listener);
+    widget.log('didChangeDependencies ${_position?.pixels}');
+  }
+
+  @override
+  void dispose() {
+    _position?.removeListener(listener);
+    super.dispose();
+  }
+
+  @override
+  Widget build(BuildContext context) => widget.child;
+
+  void listener() {
+    widget.log('listener ${_position?.pixels}');
+  }
+}
+
+void main() {
+  testWidgets(
+      'Scrollable.of() dependent rebuilds when Scrollable position changes',
+      (WidgetTester tester) async {
+    String logValue;
+    final ScrollController controller = new ScrollController();
+
+    // Changing the SingleChildScrollView's physics causes the
+    // ScrollController's ScrollPosition to be rebuilt.
+
+    Widget buildFrame(ScrollPhysics physics) {
+      return new SingleChildScrollView(
+        controller: controller,
+        physics: physics,
+        child: new ScrollPositionListener(
+          log: (String s) {
+            logValue = s;
+          },
+          child: const SizedBox(height: 400.0),
+        ),
+      );
+    }
+
+    await tester.pumpWidget(buildFrame(null));
+    // TODO(yjbanov): Flutter expects "N.0", but in JS we get "N" because of the
+    //                differences in numerics across platforms.
+    expect(logValue, 'didChangeDependencies 0');
+
+    controller.jumpTo(100.0);
+    expect(logValue, 'listener 100');
+
+    await tester.pumpWidget(buildFrame(const ClampingScrollPhysics()));
+    expect(logValue, 'didChangeDependencies 100');
+
+    controller.jumpTo(200.0);
+    expect(logValue, 'listener 200');
+
+    controller.jumpTo(300.0);
+    expect(logValue, 'listener 300');
+
+    await tester.pumpWidget(buildFrame(const BouncingScrollPhysics()));
+    expect(logValue, 'didChangeDependencies 300');
+
+    controller.jumpTo(400.0);
+    expect(logValue, 'listener 400');
+  });
+}