Add:创建 flutter go web 版

packages/flutter_web/test/rendering/constraints_test.dart

@@ -0,0 +1,71 @@
+// 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:test/test.dart';
+import 'package:flutter_web/material.dart';
+import 'package:flutter_web/rendering.dart';
+import 'package:flutter_web_ui/ui.dart';
+
+void main() {
+  test('RenderFractionallySizedBox constraints', () {
+    RenderBox root, leaf, test;
+    root = new RenderPositionedBox(
+      child: new RenderConstrainedBox(
+        additionalConstraints:
+            new BoxConstraints.tight(const Size(200.0, 200.0)),
+        child: test = new RenderFractionallySizedOverflowBox(
+          widthFactor: 2.0,
+          heightFactor: 0.5,
+          child: leaf = new RenderConstrainedBox(
+            additionalConstraints: const BoxConstraints.expand(),
+          ),
+        ),
+      ),
+    );
+    root.layout(BoxConstraints.tight(Size(800.0, 600.0)));
+    expect(root.size.width, equals(800.0));
+    expect(root.size.height, equals(600.0));
+    expect(test.size.width, equals(200.0));
+    expect(test.size.height, equals(200.0));
+    expect(leaf.size.width, equals(400.0));
+    expect(leaf.size.height, equals(100.0));
+  });
+
+  test('BoxConstraints with NaN', () {
+    String result;
+    final String noException = 'no exception';
+    result = noException;
+    try {
+      const BoxConstraints constraints = const BoxConstraints(
+          minWidth: double.nan,
+          maxWidth: double.nan,
+          minHeight: 2.0,
+          maxHeight: double.nan);
+      assert(constraints.debugAssertIsValid());
+    } catch (e) {
+      result = '$e';
+    }
+    expect(result, isNot(noException));
+
+    result = noException;
+    try {
+      const BoxConstraints constraints =
+          const BoxConstraints(minHeight: double.nan);
+      assert(constraints.debugAssertIsValid());
+    } catch (e) {
+      result = '$e';
+    }
+    expect(result, isNot(noException));
+
+    result = noException;
+    try {
+      const BoxConstraints constraints =
+          const BoxConstraints(minHeight: double.nan, maxWidth: 0.0 / 0.0);
+      assert(constraints.debugAssertIsValid());
+    } catch (e) {
+      result = '$e';
+    }
+    expect(result, isNot(noException));
+  });
+}