Adding a mechanism to 'upgrade' the Dart type of elements

tests/html/custom/element_upgrade_test.dart

+// Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+library register_element_proxy_test;
+
+import 'dart:async';
+import 'dart:html';
+import 'dart:js' as js;
+import 'package:unittest/html_config.dart';
+import 'package:unittest/unittest.dart';
+import '../utils.dart';
+
+class FooElement extends HtmlElement {
+  static final tag = 'x-foo';
+
+  final int initializedField = 666;
+  js.JsObject _proxy;
+
+  factory FooElement() => new Element.tag(tag);
+  FooElement.created() : super.created() {
+    _proxy = new js.JsObject.fromBrowserObject(this);

[Jennifer Messerly, 2014/03/07 00:00:49]

I wonder if, eventually, we can find a way to remove the _proxy object. Since we
already have a Dart object (FooElement in this example).

This seems like a good first step though.

+  }
+
+  String doSomething() => _proxy.callMethod('doSomething');
+
+  bool get fooCreated => _proxy['fooCreated'];
+}
+
+main() {
+  useHtmlConfiguration();
+
+  var registered = false;
+  var upgrader;
+  setUp(() => customElementsReady.then((_) {
+    if (!registered) {
+      registered = true;
+      upgrader = document.createElementUpgrader(FooElement);
+      js.context['upgradeListener'] = (e) {
+        upgrader.upgrade(e);
+      };
+    }
+  }));
+
+  test('created gets proxied', () {
+    var element = document.createElement(FooElement.tag);
+    expect(element is FooElement, isTrue);
+    expect(element.initializedField, 666);
+    expect(element.text, 'constructed');
+
+    js.context.callMethod('validateIsFoo', [element]);
+
+    expect(element.doSomething(), 'didSomething');
+    expect(element.fooCreated, true);
+  });
+
+  test('dart constructor works', () {
+    var element = new FooElement();
+    expect(element is FooElement, isTrue);
+    expect(element.text, 'constructed');
+
+    js.context.callMethod('validateIsFoo', [element]);
+
+    expect(element.doSomething(), 'didSomething');
+  });
+
+  test('cannot create upgrader for interfaces', () {
+    expect(() {
+      document.createElementUpgrader(HtmlElementInterface);
+    }, throws);
+  });
+
+  test('cannot upgrade interfaces', () {
+    expect(() {
+      upgrader.upgrade(new HtmlElementInterface());
+    }, throws);
+  });
+
+  test('cannot upgrade more than once', () {
+    var fooElement = new FooElement();
+    expect(() {
+      upgrader.upgrade(fooElement);
+    }, throws);
+  });
+
+  test('cannot upgrade non-matching elements', () {

[Jennifer Messerly, 2014/03/07 00:00:49]

maybe a test that you can't upgrade a Dart custom element?

[blois, 2014/04/01 19:52:22]

Done.

+    expect(() {
+      upgrader.upgrade(new DivElement());
+    }, throws);
+  });
+
+  test('cannot upgrade non-matching elements', () {

[Jennifer Messerly, 2014/03/07 00:00:49]

this seems identical to above test.

[blois, 2014/04/01 19:52:22]

Done.

+    expect(() {
+      upgrader.upgrade(new DivElement());
+    }, throws);
+  });
+
+  test('can upgrade with extendsTag', () {
+    var upgrader =
+        document.createElementUpgrader(CustomDiv, extendsTag: 'div');
+    var div = new DivElement();
+    var customDiv = upgrader.upgrade(div);
+    expect(customDiv is CustomDiv, isTrue);
+
+    var htmlElement = document.createElement('not-registered');
+    expect(() {
+      upgrader.upgrade(htmlElement);
+    }, throws);
+  });
+}
+
+class HtmlElementInterface implements HtmlElement {
+  HtmlElementInterface.created();
+}
+
+class CustomDiv extends DivElement {
+  CustomDiv.created() : super.created();
+}