Add:创建 flutter go web 版

packages/flutter_web/test/widgets/baseline_test.dart

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+// 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/material.dart';
+
+void main() {
+  testWidgets('Baseline - control test', (WidgetTester tester) async {
+    await tester.pumpWidget(
+      const Center(
+        child: DefaultTextStyle(
+          style: TextStyle(
+            fontFamily: 'Ahem',
+            fontSize: 100.0,
+          ),
+          child: Text('X', textDirection: TextDirection.ltr),
+        ),
+      ),
+    );
+    expect(tester.renderObject<RenderBox>(find.text('X')).size,
+        const Size(100.0, 100.0));
+  });
+
+  testWidgets('Baseline - position test', (WidgetTester tester) async {
+    await tester.pumpWidget(
+      const Center(
+        child: Baseline(
+          baseline: 180.0,
+          baselineType: TextBaseline.alphabetic,
+          child: DefaultTextStyle(
+            style: TextStyle(
+              fontFamily: 'Ahem',
+              fontSize: 100.0,
+            ),
+            child: Text('X', textDirection: TextDirection.ltr),
+          ),
+        ),
+      ),
+    );
+    expect(tester.renderObject<RenderBox>(find.text('X')).size,
+        const Size(100.0, 100.0));
+    expect(tester.renderObject<RenderBox>(find.byType(Baseline)).size,
+        within<Size>(from: const Size(100.0, 200.0), distance: 0.001));
+  });
+
+  testWidgets('Chip caches baseline', (WidgetTester tester) async {
+    int calls = 0;
+    await tester.pumpWidget(
+      MaterialApp(
+        home: Material(
+          child: Baseline(
+            baseline: 100.0,
+            baselineType: TextBaseline.alphabetic,
+            child: Chip(
+              label: BaselineDetector(() {
+                calls += 1;
+              }),
+            ),
+          ),
+        ),
+      ),
+    );
+    expect(calls, 1);
+    await tester.pump();
+    expect(calls, 1);
+    tester
+        .renderObject<RenderBaselineDetector>(find.byType(BaselineDetector))
+        .dirty();
+    await tester.pump();
+    expect(calls, 2);
+  });
+
+  testWidgets('ListTile caches baseline', (WidgetTester tester) async {
+    int calls = 0;
+    await tester.pumpWidget(
+      MaterialApp(
+        home: Material(
+          child: Baseline(
+            baseline: 100.0,
+            baselineType: TextBaseline.alphabetic,
+            child: ListTile(
+              title: BaselineDetector(() {
+                calls += 1;
+              }),
+            ),
+          ),
+        ),
+      ),
+    );
+    expect(calls, 1);
+    await tester.pump();
+    expect(calls, 1);
+    tester
+        .renderObject<RenderBaselineDetector>(find.byType(BaselineDetector))
+        .dirty();
+    await tester.pump();
+    expect(calls, 2);
+  });
+}
+
+class BaselineDetector extends LeafRenderObjectWidget {
+  const BaselineDetector(this.callback);
+
+  final VoidCallback callback;
+
+  @override
+  RenderBaselineDetector createRenderObject(BuildContext context) =>
+      RenderBaselineDetector(callback);
+
+  @override
+  void updateRenderObject(
+      BuildContext context, RenderBaselineDetector renderObject) {
+    renderObject.callback = callback;
+  }
+}
+
+class RenderBaselineDetector extends RenderBox {
+  RenderBaselineDetector(this.callback);
+
+  VoidCallback callback;
+
+  @override
+  bool get sizedByParent => true;
+
+  @override
+  double computeMinIntrinsicWidth(double height) => 0.0;
+
+  @override
+  double computeMaxIntrinsicWidth(double height) => 0.0;
+
+  @override
+  double computeMinIntrinsicHeight(double width) => 0.0;
+
+  @override
+  double computeMaxIntrinsicHeight(double width) => 0.0;
+
+  @override
+  double computeDistanceToActualBaseline(TextBaseline baseline) {
+    if (callback != null) callback();
+    return 0.0;
+  }
+
+  void dirty() {
+    markNeedsLayout();
+  }
+
+  @override
+  void performResize() {
+    size = constraints.smallest;
+  }
+
+  @override
+  void paint(PaintingContext context, Offset offset) {}
+}