Maintain referential integrity of proxy instances in dart:js

tests/html/js_test.dart

Index: tests/html/js_test.dart
diff --git a/tests/html/js_test.dart b/tests/html/js_test.dart
index 290a0fbb85e5b77cdcd43b4cacc06109668ef362..7a0abbbbfd9cfafba84794a71601f19dfce387db 100644
--- a/tests/html/js_test.dart
+++ b/tests/html/js_test.dart
@@ -124,6 +124,10 @@ function Baz(p1,p2,p3,p4,p5,p6,p7,p8,p9,p10,p11) {
   this.f10 = p10;
   this.f11 = p11;
 }
+
+function identical(o1, o2) {
+  return o1 === o2;
+}
 """;
   document.body.append(script);
 }
@@ -147,14 +151,63 @@ class Color implements Serializable<String> {
   String toJs() => this._value;
 }
 
+class TestDartObject {}
+
 main() {
   _injectJs();
   useHtmlConfiguration();
 
-  test('context instances should be identical', () {
-    var c1 = context;
-    var c2 = context;
-    expect(identical(c1, c2), isTrue);
+  group('identity', () {
+
+    test('context instances should be identical', () {
+      var c1 = context;
+      var c2 = context;
+      expect(identical(c1, c2), isTrue);
+    });
+
+    test('identical JS objects should have identical proxies', () {
+      var o1 = new JsObject(context['Foo'], [1]);
+      context['f1'] = o1;
+      var o2 = context['f1'];
+      expect(identical(o1, o2), isTrue);
+    });
+
+    test('identical JS functions should have identical proxies', () {
+      var f1 = context['Object'];
+      var f2 = context['Object'];
+      expect(identical(f1, f2), isTrue);
+    });
+
+    test('identical Dart objects should have identical proxies', () {
+      var o1 = new TestDartObject();
+      expect(context.callMethod('identical', [o1, o1]), isTrue);
+    });
+
+    test('identical Dart functions should have identical proxies', () {
+      var f1 = () => print("I'm a Function!");
+      expect(context.callMethod('identical', [f1, f1]), isTrue);
+    });
+
+    // TODO(justinfagnani): old tests duplicate checks above, remove
+    // on test next cleanup pass
+    test('test proxy equality', () {
+      var foo1 = new JsObject(context['Foo'], [1]);
+      var foo2 = new JsObject(context['Foo'], [2]);
+      context['foo1'] = foo1;
+      context['foo2'] = foo2;
+      expect(foo1, isNot(equals(context['foo2'])));
+      expect(foo2, same(context['foo2']));
+      context.deleteProperty('foo1');
+      context.deleteProperty('foo2');
+    });
+
+    test('retrieve same dart Object', () {
+      final date = new DateTime.now();
+      context['dartDate'] = date;
+      expect(context['dartDate'], same(date));
+      context.deleteProperty('dartDate');
+    });
+
   });
 
   test('read global field', () {
@@ -411,15 +464,6 @@ main() {
     expect(result, 42);
   });
 
-  test('test proxy equality', () {
-    var foo1 = new JsObject(context['Foo'], [1]);
-    var foo2 = new JsObject(context['Foo'], [2]);
-    context['foo'] = foo1;
-    context['foo'] = foo2;
-    expect(foo1, isNot(equals(context['foo'])));
-    expect(foo2, equals(context['foo']));
-  });
-
   test('test instanceof', () {
     var foo = new JsObject(context['Foo'], [1]);
     expect(foo.instanceof(context['Foo']), isTrue);
@@ -461,12 +505,6 @@ main() {
     expect(context['Bar']['foo'], "property_value");
   });
 
-  test('retrieve same dart Object', () {
-    final date = new DateTime.now();
-    context['dartDate'] = date;
-    expect(context['dartDate'], equals(date));
-  });
-
   test('usage of Serializable', () {
     final red = Color.RED;
     context['color'] = red;