[url_launcher_web] Fix Link misalignment issue (flutter#3476)

The Link widget builds a Stack on the web. The Stack by default loosens the constraints passed by the parent. This is what was causing the misalignment.

In order to fix it, we just need to pass fit: StackFit.passthrough to the Stack.

Author: mdebbar

packages/url_launcher/url_launcher_web/CHANGELOG.md

@@ -1,3 +1,7 @@
+# 0.1.5+3
+
+- Fix Link misalignment [issue](https://github.com/flutter/flutter/issues/70053).
+
 # 0.1.5+2
 
 - Update Flutter SDK constraint.

packages/url_launcher/url_launcher_web/lib/src/link.dart

@@ -66,6 +66,7 @@ class WebLinkDelegateState extends State<WebLinkDelegate> {
   @override
   Widget build(BuildContext context) {
     return Stack(
+      fit: StackFit.passthrough,
       children: <Widget>[
         widget.link.builder(
           context,

packages/url_launcher/url_launcher_web/pubspec.yaml

@@ -4,7 +4,7 @@ homepage: https://github.com/flutter/plugins/tree/master/packages/url_launcher/u
 # 0.1.y+z is compatible with 1.0.0, if you land a breaking change bump
 # the version to 2.0.0.
 # See more details: https://github.com/flutter/flutter/wiki/Package-migration-to-1.0.0
-version: 0.1.5+2
+version: 0.1.5+3
 
 flutter:
   plugin:

packages/url_launcher/url_launcher_web/test/lib/main.dart

@@ -17,6 +17,9 @@ class MyApp extends StatefulWidget {
 class _MyAppState extends State<MyApp> {
   @override
   Widget build(BuildContext context) {
-    return Text('Testing... Look at the console output for results!');
+    return Directionality(
+      textDirection: TextDirection.ltr,
+      child: Text('Testing... Look at the console output for results!'),
+    );
   }
 }

packages/url_launcher/url_launcher_web/test/test_driver/url_launcher_web_integration.dart

@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+// @dart = 2.9
 import 'dart:html' as html;
 import 'dart:js_util';
 import 'package:flutter/widgets.dart';
@@ -271,6 +272,38 @@ void main() {
       expect(anchor.getAttribute('href'), uri2.toString());
       expect(anchor.getAttribute('target'), '_self');
     });
+
+    testWidgets('sizes itself correctly', (WidgetTester tester) async {
+      final Key containerKey = GlobalKey();
+      final Uri uri = Uri.parse('http://foobar');
+      await tester.pumpWidget(Directionality(
+        textDirection: TextDirection.ltr,
+        child: Center(
+          child: ConstrainedBox(
+            constraints: BoxConstraints.tight(Size(100.0, 100.0)),
+            child: WebLinkDelegate(TestLinkInfo(
+              uri: uri,
+              target: LinkTarget.blank,
+              builder: (BuildContext context, FollowLink followLink) {
+                return Container(
+                  key: containerKey,
+                  child: SizedBox(width: 50.0, height: 50.0),
+                );
+              },
+            )),
+          ),
+        ),
+      ));
+      await tester.pumpAndSettle();
+
+      final Size containerSize = tester.getSize(find.byKey(containerKey));
+      // The Stack widget inserted by the `WebLinkDelegate` shouldn't loosen the
+      // constraints before passing them to the inner container. So the inner
+      // container should respect the tight constraints given by the ancestor
+      // `ConstrainedBox` widget.
+      expect(containerSize.width, 100.0);
+      expect(containerSize.height, 100.0);
+    });
   });
 }
 

packages/url_launcher/url_launcher_web/test/test_driver/url_launcher_web_integration_test.dart

@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+// @dart = 2.9
 import 'package:integration_test/integration_test_driver.dart';
 
 Future<void> main() async => integrationDriver();