Add:创建 flutter go web 版

packages/flutter_web/test/rendering/stack_rendering_test.dart

@@ -0,0 +1,92 @@
+// 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/rendering.dart';
+import '../flutter_test_alternative.dart';
+
+import 'rendering_tester.dart';
+
+void main() {
+  test('Stack can layout with top, right, bottom, left 0.0', () {
+    final RenderBox size = RenderConstrainedBox(
+        additionalConstraints: BoxConstraints.tight(const Size(100.0, 100.0)));
+
+    final RenderBox red = RenderDecoratedBox(
+        decoration: const BoxDecoration(
+          color: Color(0xFFFF0000),
+        ),
+        child: size);
+
+    final RenderBox green = RenderDecoratedBox(
+      decoration: const BoxDecoration(
+        color: Color(0xFFFF0000),
+      ),
+    );
+
+    final RenderBox stack = RenderStack(
+      textDirection: TextDirection.ltr,
+      children: <RenderBox>[red, green],
+    );
+    final StackParentData greenParentData = green.parentData;
+    greenParentData
+      ..top = 0.0
+      ..right = 0.0
+      ..bottom = 0.0
+      ..left = 0.0;
+
+    layout(stack, constraints: const BoxConstraints());
+
+    expect(stack.size.width, equals(100.0));
+    expect(stack.size.height, equals(100.0));
+
+    expect(red.size.width, equals(100.0));
+    expect(red.size.height, equals(100.0));
+
+    expect(green.size.width, equals(100.0));
+    expect(green.size.height, equals(100.0));
+  });
+
+  test('Stack can layout with no children', () {
+    final RenderBox stack = RenderStack(
+      textDirection: TextDirection.ltr,
+      children: <RenderBox>[],
+    );
+
+    layout(stack, constraints: BoxConstraints.tight(const Size(100.0, 100.0)));
+
+    expect(stack.size.width, equals(100.0));
+    expect(stack.size.height, equals(100.0));
+  });
+
+  group('RenderIndexedStack', () {
+    test('visitChildrenForSemantics only visits displayed child', () {
+      final RenderBox child1 = RenderConstrainedBox(
+          additionalConstraints:
+              BoxConstraints.tight(const Size(100.0, 100.0)));
+      final RenderBox child2 = RenderConstrainedBox(
+          additionalConstraints:
+              BoxConstraints.tight(const Size(100.0, 100.0)));
+      final RenderBox child3 = RenderConstrainedBox(
+          additionalConstraints:
+              BoxConstraints.tight(const Size(100.0, 100.0)));
+      final RenderBox stack = RenderIndexedStack(
+        index: 1,
+        textDirection: TextDirection.ltr,
+        children: <RenderBox>[child1, child2, child3],
+      );
+
+      final List<RenderObject> visitedChildren = <RenderObject>[];
+      final RenderObjectVisitor visitor = (RenderObject child) {
+        visitedChildren.add(child);
+      };
+
+      stack.visitChildrenForSemantics(visitor);
+
+      expect(visitedChildren, hasLength(1));
+      expect(visitedChildren.first, child2);
+    });
+  });
+
+  // More tests in ../widgets/stack_test.dart
+}