big update to observe, template_binding, polymer

pkg/template_binding/test/node_bind_test.dart

Index: pkg/template_binding/test/node_bind_test.dart
diff --git a/pkg/template_binding/test/node_bind_test.dart b/pkg/template_binding/test/node_bind_test.dart
index fbedcfa3271724e2151f29ee29d02f95bc3800c7..93bcd8fe2ff1fea8cdd5148e366ab5516552a853 100644
--- a/pkg/template_binding/test/node_bind_test.dart
+++ b/pkg/template_binding/test/node_bind_test.dart
@@ -4,11 +4,12 @@
 
 library template_binding.test.node_bind_test;
 
+import 'dart:async';
 import 'dart:html';
 
-import 'package:observe/observe.dart' show toObservable, PathObserver;
+import 'package:observe/observe.dart'
+    show toObservable, PathObserver, PropertyPath;
 import 'package:template_binding/template_binding.dart' show nodeBind;
-import 'package:template_binding/src/node_binding.dart' show getObserverForTest;
 
 import 'package:unittest/html_config.dart';
 import 'package:unittest/unittest.dart';
@@ -17,7 +18,7 @@ import 'utils.dart';
 // Note: this file ported from
 // https://github.com/toolkitchen/mdv/blob/master/tests/node_bindings.js
 
-main() {
+main() => dirtyCheckZone().run(() {
   useHtmlConfiguration();
 
   setUp(() {
@@ -29,147 +30,162 @@ main() {
     testDiv = null;
   });
 
-
   group('Text bindings', testBindings);
   group('Element attribute bindings', elementBindings);
   group('Form Element bindings', formBindings);
-}
+});
 
 testBindings() {
-  observeTest('Basic', () {
+  test('Basic', () {
     var text = new Text('hi');
     var model = toObservable({'a': 1});
-    nodeBind(text).bind('text', model, 'a');
+    nodeBind(text).bind('text', new PathObserver(model, 'a'));
     expect(text.text, '1');
 
     model['a'] = 2;
-    performMicrotaskCheckpoint();
-    expect(text.text, '2');
-
-    nodeBind(text).unbind('text');
-    model['a'] = 3;
-    performMicrotaskCheckpoint();
-    expect(text.text, '2');
+    return new Future(() {
+      expect(text.text, '2');
+
+      nodeBind(text).unbind('text');
+      model['a'] = 3;
+    }).then(endOfMicrotask).then((_) {
+      // TODO(rafaelw): Throw on binding to unavailable property?
+      expect(text.text, '2');
+    });
+  });
 
-    // TODO(rafaelw): Throw on binding to unavailable property?
+  test('oneTime', () {
+    var text = new Text('hi');
+    nodeBind(text).bind('text', 1, oneTime: true);
+    expect(text.text, '1');
   });
 
-  observeTest('No Path', () {
+  test('No Path', () {
     var text = new Text('hi');
     var model = 1;
-    nodeBind(text).bind('text', model);
+    nodeBind(text).bind('text', new PathObserver(model));
     expect(text.text, '1');
   });
 
-  observeTest('Path unreachable', () {
+  test('Path unreachable', () {
     var text = testDiv.append(new Text('hi'));
     var model = 1;
-    nodeBind(text).bind('text', model, 'a');
+    nodeBind(text).bind('text', new PathObserver(model, 'a'));
     expect(text.text, '');
   });
 
-  observeTest('Observer is Model', () {
+  test('Observer is Model', () {
     var text = new Text('');
     var model = toObservable({'a': {'b': {'c': 1}}});
     var observer = new PathObserver(model, 'a.b.c');
-    nodeBind(text).bind('text', observer, 'value');
+    nodeBind(text).bind('text', observer);
     expect(text.text, '1');
 
     var binding = nodeBind(text).bindings['text'];
-    expect(binding, isNotNull);
-    expect(getObserverForTest(binding), observer,
-        reason: 'should reuse observer');
+    expect(binding, observer, reason: 'should reuse observer');
 
     model['a']['b']['c'] = 2;
-    performMicrotaskCheckpoint();
-    expect(text.text, '2');
-    nodeBind(text).unbind('text');
+    return new Future(() {
+      expect(text.text, '2');
+      nodeBind(text).unbind('text');
+    });
   });
 }
 
 elementBindings() {
-  observeTest('Basic', () {
+  test('Basic', () {
     var el = new DivElement();
     var model = toObservable({'a': '1'});
-    nodeBind(el).bind('foo', model, 'a');
-    performMicrotaskCheckpoint();
-    expect(el.attributes['foo'], '1');
-
-    model['a'] = '2';
-    performMicrotaskCheckpoint();
-    expect(el.attributes['foo'], '2');
-
-    model['a'] = 232.2;
-    performMicrotaskCheckpoint();
-    expect(el.attributes['foo'], '232.2');
-
-    model['a'] = 232;
-    performMicrotaskCheckpoint();
-    expect(el.attributes['foo'], '232');
+    nodeBind(el).bind('foo', new PathObserver(model, 'a'));
+
+    return new Future(() {
+      expect(el.attributes['foo'], '1');
+      model['a'] = '2';
+    }).then(endOfMicrotask).then((_) {
+      expect(el.attributes['foo'], '2');
+      model['a'] = 232.2;
+    }).then(endOfMicrotask).then((_) {
+      expect(el.attributes['foo'], '232.2');
+      model['a'] = 232;
+    }).then(endOfMicrotask).then((_) {
+      expect(el.attributes['foo'], '232');
+      model['a'] = null;
+    }).then(endOfMicrotask).then((_) {
+      expect(el.attributes['foo'], '');
+    });
+  });
 
-    model['a'] = null;
-    performMicrotaskCheckpoint();
-    expect(el.attributes['foo'], '');
+  test('oneTime', () {
+    var el = testDiv.append(new DivElement());
+    var model = toObservable({'a': '1'});
+    nodeBind(el).bind('foo', 1, oneTime: true);
+    expect('1', el.attributes['foo']);
   });
 
-  observeTest('No Path', () {
+  test('No Path', () {
     var el = testDiv.append(new DivElement());
     var model = 1;
-    nodeBind(el).bind('foo', model);
-    expect(el.attributes['foo'], '1');
+    nodeBind(el).bind('foo', new PathObserver(model));
+    return new Future(() {
+      expect(el.attributes['foo'], '1');
+    });
   });
 
-  observeTest('Path unreachable', () {
+  test('Path unreachable', () {
     var el = testDiv.append(new DivElement());
     var model = toObservable({});
-    nodeBind(el).bind('foo', model, 'bar');
-    expect(el.attributes['foo'], '');
+    nodeBind(el).bind('foo', new PathObserver(model, 'bar'));
+    return new Future(() {
+      expect(el.attributes['foo'], '');
+    });
   });
 
-  observeTest('Dashes', () {
+  test('Dashes', () {
     var el = testDiv.append(new DivElement());
     var model = toObservable({'a': '1'});
-    nodeBind(el).bind('foo-bar', model, 'a');
-    performMicrotaskCheckpoint();
-    expect(el.attributes['foo-bar'], '1');
+    nodeBind(el).bind('foo-bar', new PathObserver(model, 'a'));
+    return new Future(() {
+      expect(el.attributes['foo-bar'], '1');
+      model['a'] = '2';
 
-    model['a'] = '2';
-    performMicrotaskCheckpoint();
-    expect(el.attributes['foo-bar'], '2');
+    }).then(endOfMicrotask).then((_) {
+      expect(el.attributes['foo-bar'], '2');
+    });
   });
 
-  observeTest('Element.id, Element.hidden?', () {
+  test('Element.id, Element.hidden?', () {
     var element = new DivElement();
     var model = toObservable({'a': 1, 'b': 2});
-    nodeBind(element).bind('hidden?', model, 'a');
-    nodeBind(element).bind('id', model, 'b');
+    nodeBind(element).bind('hidden?', new PathObserver(model, 'a'));
+    nodeBind(element).bind('id', new PathObserver(model, 'b'));
 
     expect(element.attributes, contains('hidden'));
     expect(element.attributes['hidden'], '');
     expect(element.id, '2');
 
     model['a'] = null;
-    performMicrotaskCheckpoint();
-    expect(element.attributes, isNot(contains('hidden')),
-        reason: 'null is false-y');
-
-    model['a'] = false;
-    performMicrotaskCheckpoint();
-    expect(element.attributes, isNot(contains('hidden')));
-
-    model['a'] = 'foo';
-    model['b'] = 'x';
-    performMicrotaskCheckpoint();
-    expect(element.attributes, contains('hidden'));
-    expect(element.attributes['hidden'], '');
-    expect(element.id, 'x');
+    return new Future(() {
+      expect(element.attributes, isNot(contains('hidden')),
+          reason: 'null is false-y');
+
+      model['a'] = false;
+    }).then(endOfMicrotask).then((_) {
+      expect(element.attributes, isNot(contains('hidden')));
+
+      model['a'] = 'foo';
+      model['b'] = 'x';
+    }).then(endOfMicrotask).then((_) {
+      expect(element.attributes, contains('hidden'));
+      expect(element.attributes['hidden'], '');
+      expect(element.id, 'x');
+    });
   });
 
-  observeTest('Element.id - path unreachable', () {
+  test('Element.id - path unreachable', () {
     var element = testDiv.append(new DivElement());
     var model = toObservable({});
-    nodeBind(element).bind('id', model, 'a');
-    expect(element.id, '');
+    nodeBind(element).bind('id', new PathObserver(model, 'a'));
+    return new Future(() => expect(element.id, ''));
   });
 }
 
@@ -178,237 +194,284 @@ formBindings() {
     var el = new Element.tag(tagName);
     testDiv.nodes.add(el);
     var model = toObservable({'x': 42});
-    nodeBind(el).bind('value', model, 'x');
+    nodeBind(el).bind('value', new PathObserver(model, 'x'));
     expect(el.value, '42');
 
     model['x'] = 'Hi';
     expect(el.value, '42', reason: 'changes delivered async');
-    performMicrotaskCheckpoint();
-    expect(el.value, 'Hi');
+    return new Future(() {
+      expect(el.value, 'Hi');
 
-    el.value = 'changed';
-    dispatchEvent('input', el);
-    expect(model['x'], 'changed');
+      el.value = 'changed';
+      dispatchEvent('input', el);
+      expect(model['x'], 'changed');
 
-    nodeBind(el).unbind('value');
+      nodeBind(el).unbind('value');
 
-    el.value = 'changed again';
-    dispatchEvent('input', el);
-    expect(model['x'], 'changed');
+      el.value = 'changed again';
+      dispatchEvent('input', el);
+      expect(model['x'], 'changed');
 
-    nodeBind(el).bind('value', model, 'x');
-    model['x'] = null;
-    performMicrotaskCheckpoint();
-    expect(el.value, '');
+      nodeBind(el).bind('value', new PathObserver(model, 'x'));
+      model['x'] = null;
+    }).then(endOfMicrotask).then((_) {
+      expect(el.value, '');
+    });
+  }
+
+  inputTextAreaValueOnetime(String tagName) {
+    var el = testDiv.append(new Element.tag(tagName));
+    nodeBind(el).bind('value', 42, oneTime: true);
+    expect(el.value, '42');
   }
 
   inputTextAreaNoPath(String tagName) {
     var el = testDiv.append(new Element.tag(tagName));
     var model = 42;
-    nodeBind(el).bind('value', model);
+    nodeBind(el).bind('value', new PathObserver(model));
     expect(el.value, '42');
   }
 
   inputTextAreaPathUnreachable(String tagName) {
     var el = testDiv.append(new Element.tag(tagName));
     var model = toObservable({});
-    nodeBind(el).bind('value', model, 'a');
+    nodeBind(el).bind('value', new PathObserver(model, 'a'));
     expect(el.value, '');
   }
 
-  observeTest('Input.value',
+  test('Input.value',
       () => inputTextAreaValueTest('input'));
-  observeTest('Input.value - no path',
+
+  test('Input.value - oneTime',
+      () => inputTextAreaValueOnetime('input'));
+
+  test('Input.value - no path',
       () => inputTextAreaNoPath('input'));
-  observeTest('Input.value - path unreachable',
+
+  test('Input.value - path unreachable',
       () => inputTextAreaPathUnreachable('input'));
-  observeTest('TextArea.value',
+
+  test('TextArea.value',
       () => inputTextAreaValueTest('textarea'));
-  observeTest('TextArea.value - no path',
+
+  test('TextArea.value - oneTime',
+      () => inputTextAreaValueOnetime('textarea'));
+
+  test('TextArea.value - no path',
       () => inputTextAreaNoPath('textarea'));
-  observeTest('TextArea.value - path unreachable',
+
+  test('TextArea.value - path unreachable',
       () => inputTextAreaPathUnreachable('textarea'));
 
-  observeTest('Radio Input', () {
+  test('Radio Input', () {
     var input = new InputElement();
     input.type = 'radio';
     var model = toObservable({'x': true});
-    nodeBind(input).bind('checked', model, 'x');
+    nodeBind(input).bind('checked', new PathObserver(model, 'x'));
     expect(input.checked, true);
 
     model['x'] = false;
     expect(input.checked, true);
-    performMicrotaskCheckpoint();
-    expect(input.checked, false,reason: 'model change should update checked');
+    return new Future(() {
+      expect(input.checked, false,reason: 'model change should update checked');
 
-    input.checked = true;
-    dispatchEvent('change', input);
-    expect(model['x'], true, reason: 'input.checked should set model');
+      input.checked = true;
+      dispatchEvent('change', input);
+      expect(model['x'], true, reason: 'input.checked should set model');
 
-    nodeBind(input).unbind('checked');
+      nodeBind(input).unbind('checked');
 
-    input.checked = false;
-    dispatchEvent('change', input);
-    expect(model['x'], true,
-        reason: 'disconnected binding should not fire');
+      input.checked = false;
+      dispatchEvent('change', input);
+      expect(model['x'], true,
+          reason: 'disconnected binding should not fire');
+    });
   });
 
-  observeTest('Input.value - user value rejected', () {
+  test('Input.value - user value rejected', () {
     var model = toObservable({'val': 'ping'});
 
     var el = new InputElement();
-    nodeBind(el).bind('value', model, 'val');
-    performMicrotaskCheckpoint();
-    expect(el.value, 'ping');
-
-    el.value = 'pong';
-    dispatchEvent('input', el);
-    expect(model['val'], 'pong');
-
-    // Try a deep path.
-    model = toObservable({'a': {'b': {'c': 'ping'}}});
-
-    nodeBind(el).bind('value', model, 'a.b.c');
-    performMicrotaskCheckpoint();
-    expect(el.value, 'ping');
-
-    el.value = 'pong';
-    dispatchEvent('input', el);
-    expect(new PathObserver(model, 'a.b.c').value, 'pong');
-
-    // Start with the model property being absent.
-    model['a']['b'].remove('c');
-    performMicrotaskCheckpoint();
-    expect(el.value, '');
-
-    el.value = 'pong';
-    dispatchEvent('input', el);
-    expect(new PathObserver(model, 'a.b.c').value, 'pong');
-    performMicrotaskCheckpoint();
-
-    // Model property unreachable (and unsettable).
-    model['a'].remove('b');
-    performMicrotaskCheckpoint();
-    expect(el.value, '');
-
-    el.value = 'pong';
-    dispatchEvent('input', el);
-    expect(new PathObserver(model, 'a.b.c').value, null);
+    nodeBind(el).bind('value', new PathObserver(model, 'val'));
+    return new Future(() {
+      expect(el.value, 'ping');
+
+      el.value = 'pong';
+      dispatchEvent('input', el);
+      expect(model['val'], 'pong');
+
+      // Try a deep path.
+      model = toObservable({'a': {'b': {'c': 'ping'}}});
+
+      nodeBind(el).bind('value', new PathObserver(model, 'a.b.c'));
+    }).then(endOfMicrotask).then((_) {
+      expect(el.value, 'ping');
+
+      el.value = 'pong';
+      dispatchEvent('input', el);
+      expect(new PropertyPath('a.b.c').getValueFrom(model), 'pong');
+
+      // Start with the model property being absent.
+      model['a']['b'].remove('c');
+    }).then(endOfMicrotask).then((_) {
+      expect(el.value, '');
+
+      el.value = 'pong';
+      dispatchEvent('input', el);
+      expect(new PropertyPath('a.b.c').getValueFrom(model), 'pong');
+    }).then(endOfMicrotask).then((_) {
+
+      // Model property unreachable (and unsettable).
+      model['a'].remove('b');
+    }).then(endOfMicrotask).then((_) {
+      expect(el.value, '');
+
+      el.value = 'pong';
+      dispatchEvent('input', el);
+      expect(new PropertyPath('a.b.c').getValueFrom(model), null);
+    });
   });
 
-  observeTest('(Checkbox)Input.checked', () {
+  test('Checkbox Input.checked', () {
     var el = testDiv.append(new InputElement());
     el.type = 'checkbox';
 
     var model = toObservable({'x': true});
-    nodeBind(el).bind('checked', model, 'x');
+    nodeBind(el).bind('checked', new PathObserver(model, 'x'));
     expect(el.checked, true);
 
     model['x'] = false;
     expect(el.checked, true, reason: 'changes delivered async');
-    performMicrotaskCheckpoint();
-    expect(el.checked, false);
+    return new Future(() {
+      expect(el.checked, false);
 
-    el.click();
-    expect(model['x'], true);
-    performMicrotaskCheckpoint();
+      el.click();
+      expect(model['x'], true);
+    }).then(endOfMicrotask).then((_) {
 
-    el.click();
-    expect(model['x'], false);
+      el.click();
+      expect(model['x'], false);
+    });
+  });
+
+  test('Checkbox Input.checked - oneTime', () {
+    var input = testDiv.append(new InputElement());
+    input.type = 'checkbox';
+    nodeBind(input).bind('checked', true, oneTime: true);
+    expect(input.checked, true, reason: 'checked was set');
   });
 
-  observeTest('(Checkbox)Input.checked - path unreachable', () {
+  test('Checkbox Input.checked - path unreachable', () {
     var input = testDiv.append(new InputElement());
     input.type = 'checkbox';
     var model = toObservable({});
-    nodeBind(input).bind('checked', model, 'x');
+    nodeBind(input).bind('checked', new PathObserver(model, 'x'));
     expect(input.checked, false);
   });
 
-  observeTest('(Checkbox)Input.checked 2', () {
+  test('Checkbox Input.checked 2', () {
     var model = toObservable({'val': true});
 
     var el = testDiv.append(new InputElement());
     el.type = 'checkbox';
-    nodeBind(el).bind('checked', model, 'val');
-    performMicrotaskCheckpoint();
-    expect(el.checked, true);
+    nodeBind(el).bind('checked', new PathObserver(model, 'val'));
+    return new Future(() {
+      expect(el.checked, true);
 
-    model['val'] = false;
-    performMicrotaskCheckpoint();
-    expect(el.checked, false);
+      model['val'] = false;
+    }).then(endOfMicrotask).then((_) {
+      expect(el.checked, false);
 
-    el.click();
-    expect(model['val'], true);
+      el.click();
+      expect(model['val'], true);
 
-    el.click();
-    expect(model['val'], false);
+      el.click();
+      expect(model['val'], false);
 
-    el.onClick.listen((_) {
-      expect(model['val'], true);
-    });
-    el.onChange.listen((_) {
-      expect(model['val'], true);
-    });
+      el.onClick.listen((_) {
+        expect(model['val'], true);
+      });
+      el.onChange.listen((_) {
+        expect(model['val'], true);
+      });
 
-    el.dispatchEvent(new MouseEvent('click', view: window));
+      el.dispatchEvent(new MouseEvent('click', view: window));
+    });
   });
 
-  observeTest('(Checkbox)Input.checked - binding updated on click', () {
+  test('Checkbox Input.checked - binding updated on click', () {
     var model = toObservable({'val': true});
 
     var el = new InputElement();
     testDiv.append(el);
     el.type = 'checkbox';
-    nodeBind(el).bind('checked', model, 'val');
-    performMicrotaskCheckpoint();
-    expect(el.checked, true);
+    nodeBind(el).bind('checked', new PathObserver(model, 'val'));
+    return new Future(() {
+      expect(el.checked, true);
 
-    el.onClick.listen((_) {
-      expect(model['val'], false);
-    });
+      int fired = 0;
+      el.onClick.listen((_) {
+        fired++;
+        expect(model['val'], false);
+      });
+
+      el.dispatchEvent(new MouseEvent('click', view: window));
 
-    el.dispatchEvent(new MouseEvent('click', view: window));
+      expect(fired, 1, reason: 'events dispatched synchronously');
+    });
   });
 
-  observeTest('(Checkbox)Input.checked - binding updated on change', () {
+  test('Checkbox Input.checked - binding updated on change', () {
     var model = toObservable({'val': true});
 
     var el = new InputElement();
     testDiv.append(el);
     el.type = 'checkbox';
-    nodeBind(el).bind('checked', model, 'val');
-    performMicrotaskCheckpoint();
-    expect(el.checked, true);
+    nodeBind(el).bind('checked', new PathObserver(model, 'val'));
+    return new Future(() {
+      expect(el.checked, true);
 
-    el.onChange.listen((_) {
-      expect(model['val'], false);
-    });
+      int fired = 0;
+      el.onChange.listen((_) {
+        fired++;
+        expect(model['val'], false);
+      });
 
-    el.dispatchEvent(new MouseEvent('click', view: window));
+      el.dispatchEvent(new MouseEvent('click', view: window));
+
+      expect(fired, 1, reason: 'events dispatched synchronously');
+    });
   });
 
-  observeTest('(Radio)Input.checked', () {
+  test('Radio Input.checked', () {
     var input = testDiv.append(new InputElement());
     input.type = 'radio';
     var model = toObservable({'x': true});
-    nodeBind(input).bind('checked', model, 'x');
+    nodeBind(input).bind('checked', new PathObserver(model, 'x'));
     expect(input.checked, true);
 
     model['x'] = false;
     expect(input.checked, true);
-    performMicrotaskCheckpoint();
-    expect(input.checked, false);
+    return new Future(() {
+      expect(input.checked, false);
 
-    input.checked = true;
-    dispatchEvent('change', input);
-    expect(model['x'], true);
+      input.checked = true;
+      dispatchEvent('change', input);
+      expect(model['x'], true);
 
-    nodeBind(input).unbind('checked');
+      nodeBind(input).unbind('checked');
 
-    input.checked = false;
-    dispatchEvent('change', input);
-    expect(model['x'], true);
+      input.checked = false;
+      dispatchEvent('change', input);
+      expect(model['x'], true);
+    });
+  });
+
+  test('Radio Input.checked - oneTime', () {
+    var input = testDiv.append(new InputElement());
+    input.type = 'radio';
+    nodeBind(input).bind('checked', true, oneTime: true);
+    expect(input.checked, true, reason: 'checked was set');
   });
 
   radioInputChecked2(host) {
@@ -421,69 +484,67 @@ formBindings() {
     var el1 = container.append(new InputElement());
     el1.type = 'radio';
     el1.name = RADIO_GROUP_NAME;
-    nodeBind(el1).bind('checked', model, 'val1');
+    nodeBind(el1).bind('checked', new PathObserver(model, 'val1'));
 
     var el2 = container.append(new InputElement());
     el2.type = 'radio';
     el2.name = RADIO_GROUP_NAME;
-    nodeBind(el2).bind('checked', model, 'val2');
+    nodeBind(el2).bind('checked', new PathObserver(model, 'val2'));
 
     var el3 = container.append(new InputElement());
     el3.type = 'radio';
     el3.name = RADIO_GROUP_NAME;
-    nodeBind(el3).bind('checked', model, 'val3');
+    nodeBind(el3).bind('checked', new PathObserver(model, 'val3'));
 
     var el4 = container.append(new InputElement());
     el4.type = 'radio';
     el4.name = 'othergroup';
-    nodeBind(el4).bind('checked', model, 'val4');
-
-    performMicrotaskCheckpoint();
-    expect(el1.checked, true);
-    expect(el2.checked, false);
-    expect(el3.checked, false);
-    expect(el4.checked, true);
-
-    model['val1'] = false;
-    model['val2'] = true;
-    performMicrotaskCheckpoint();
-    expect(el1.checked, false);
-    expect(el2.checked, true);
-    expect(el3.checked, false);
-    expect(el4.checked, true);
-
-    el1.checked = true;
-    dispatchEvent('change', el1);
-    expect(model['val1'], true);
-    expect(model['val2'], false);
-    expect(model['val3'], false);
-    expect(model['val4'], true);
-
-    el3.checked = true;
-    dispatchEvent('change', el3);
-    expect(model['val1'], false);
-    expect(model['val2'], false);
-    expect(model['val3'], true);
-    expect(model['val4'], true);
+    nodeBind(el4).bind('checked', new PathObserver(model, 'val4'));
+
+    return new Future(() {
+      expect(el1.checked, true);
+      expect(el2.checked, false);
+      expect(el3.checked, false);
+      expect(el4.checked, true);
+
+      model['val1'] = false;
+      model['val2'] = true;
+    }).then(endOfMicrotask).then((_) {
+      expect(el1.checked, false);
+      expect(el2.checked, true);
+      expect(el3.checked, false);
+      expect(el4.checked, true);
+
+      el1.checked = true;
+      dispatchEvent('change', el1);
+      expect(model['val1'], true);
+      expect(model['val2'], false);
+      expect(model['val3'], false);
+      expect(model['val4'], true);
+
+      el3.checked = true;
+      dispatchEvent('change', el3);
+      expect(model['val1'], false);
+      expect(model['val2'], false);
+      expect(model['val3'], true);
+      expect(model['val4'], true);
+    });
   }
 
-  observeTest('(Radio)Input.checked 2', () {
-    radioInputChecked2(testDiv);
-  });
+  test('Radio Input.checked 2', () => radioInputChecked2(testDiv));
 
-  observeTest('(Radio)Input.checked 2 - ShadowRoot', () {
-    if (!ShadowRoot.supported) return;
+  test('Radio Input.checked 2 - ShadowRoot', () {
+    if (!ShadowRoot.supported) return null;
 
-    var div = new DivElement();
-    var shadowRoot = div.createShadowRoot();
-    radioInputChecked2(shadowRoot);
-    unbindAll(shadowRoot);
+    var shadowRoot = new DivElement().createShadowRoot();
+    return radioInputChecked2(shadowRoot)
+        .whenComplete(() => unbindAll(shadowRoot));
   });
 
   radioInputCheckedMultipleForms(host) {
     var model = toObservable({'val1': true, 'val2': false, 'val3': false,
         'val4': true});
-    var RADIO_GROUP_NAME = 'observeTest';
+    var RADIO_GROUP_NAME = 'test';
 
     var container = testDiv.append(new DivElement());
     var form1 = new FormElement();
@@ -495,64 +556,65 @@ formBindings() {
     form1.append(el1);
     el1.type = 'radio';
     el1.name = RADIO_GROUP_NAME;
-    nodeBind(el1).bind('checked', model, 'val1');
+    nodeBind(el1).bind('checked', new PathObserver(model, 'val1'));
 
     var el2 = new InputElement();
     form1.append(el2);
     el2.type = 'radio';
     el2.name = RADIO_GROUP_NAME;
-    nodeBind(el2).bind('checked', model, 'val2');
+    nodeBind(el2).bind('checked', new PathObserver(model, 'val2'));
 
     var el3 = new InputElement();
     form2.append(el3);
     el3.type = 'radio';
     el3.name = RADIO_GROUP_NAME;
-    nodeBind(el3).bind('checked', model, 'val3');
+    nodeBind(el3).bind('checked', new PathObserver(model, 'val3'));
 
     var el4 = new InputElement();
     form2.append(el4);
     el4.type = 'radio';
     el4.name = RADIO_GROUP_NAME;
-    nodeBind(el4).bind('checked', model, 'val4');
-
-    performMicrotaskCheckpoint();
-    expect(el1.checked, true);
-    expect(el2.checked, false);
-    expect(el3.checked, false);
-    expect(el4.checked, true);
-
-    el2.checked = true;
-    dispatchEvent('change', el2);
-    expect(model['val1'], false);
-    expect(model['val2'], true);
-
-    // Radio buttons in form2 should be unaffected
-    expect(model['val3'], false);
-    expect(model['val4'], true);
-
-    el3.checked = true;
-    dispatchEvent('change', el3);
-    expect(model['val3'], true);
-    expect(model['val4'], false);
-
-    // Radio buttons in form1 should be unaffected
-    expect(model['val1'], false);
-    expect(model['val2'], true);
+    nodeBind(el4).bind('checked', new PathObserver(model, 'val4'));
+
+    return new Future(() {
+      expect(el1.checked, true);
+      expect(el2.checked, false);
+      expect(el3.checked, false);
+      expect(el4.checked, true);
+
+      el2.checked = true;
+      dispatchEvent('change', el2);
+      expect(model['val1'], false);
+      expect(model['val2'], true);
+
+      // Radio buttons in form2 should be unaffected
+      expect(model['val3'], false);
+      expect(model['val4'], true);
+
+      el3.checked = true;
+      dispatchEvent('change', el3);
+      expect(model['val3'], true);
+      expect(model['val4'], false);
+
+      // Radio buttons in form1 should be unaffected
+      expect(model['val1'], false);
+      expect(model['val2'], true);
+    });
   }
 
-  observeTest('(Radio)Input.checked - multiple forms', () {
-    radioInputCheckedMultipleForms(testDiv);
+  test('Radio Input.checked - multiple forms', () {
+    return radioInputCheckedMultipleForms(testDiv);
   });
 
-  observeTest('(Radio)Input.checked 2 - ShadowRoot', () {
-    if (!ShadowRoot.supported) return;
+  test('Radio Input.checked - multiple forms - ShadowRoot', () {
+    if (!ShadowRoot.supported) return null;
 
     var shadowRoot = new DivElement().createShadowRoot();
-    radioInputChecked2(shadowRoot);
-    unbindAll(shadowRoot);
+    return radioInputCheckedMultipleForms(shadowRoot)
+        .whenComplete(() => unbindAll(shadowRoot));
   });
 
-  observeTest('Select.selectedIndex', () {
+  test('Select.selectedIndex', () {
     var select = new SelectElement();
     testDiv.append(select);
     var option0 = select.append(new OptionElement());
@@ -561,16 +623,28 @@ formBindings() {
 
     var model = toObservable({'val': 2});
 
-    nodeBind(select).bind('selectedIndex', model, 'val');
-    performMicrotaskCheckpoint();
-    expect(select.selectedIndex, 2);
+    nodeBind(select).bind('selectedIndex', new PathObserver(model, 'val'));
+    return new Future(() {
+      expect(select.selectedIndex, 2);
+
+      select.selectedIndex = 1;
+      dispatchEvent('change', select);
+      expect(model['val'], 1);
+    });
+  });
+
+  test('Select.selectedIndex - oneTime', () {
+    var select = new SelectElement();
+    testDiv.append(select);
+    var option0 = select.append(new OptionElement());
+    var option1 = select.append(new OptionElement());
+    var option2 = select.append(new OptionElement());
 
-    select.selectedIndex = 1;
-    dispatchEvent('change', select);
-    expect(model['val'], 1);
+    nodeBind(select).bind('selectedIndex', 2, oneTime: true);
+    return new Future(() => expect(select.selectedIndex, 2));
   });
 
-  observeTest('Select.selectedIndex - path NaN', () {
+  test('Select.selectedIndex - invalid path', () {
     var select = new SelectElement();
     testDiv.append(select);
     var option0 = select.append(new OptionElement());
@@ -580,12 +654,11 @@ formBindings() {
 
     var model = toObservable({'val': 'foo'});
 
-    nodeBind(select).bind('selectedIndex', model, 'val');
-    performMicrotaskCheckpoint();
-    expect(select.selectedIndex, 0);
+    nodeBind(select).bind('selectedIndex', new PathObserver(model, 'val'));
+    return new Future(() => expect(select.selectedIndex, 0));
   });
 
-  observeTest('Select.selectedIndex - path unreachable', () {
+  test('Select.selectedIndex - path unreachable', () {
     var select = new SelectElement();
     testDiv.append(select);
     var option0 = select.append(new OptionElement());
@@ -595,24 +668,28 @@ formBindings() {
 
     var model = toObservable({});
 
-    nodeBind(select).bind('selectedIndex', model, 'val');
-    performMicrotaskCheckpoint();
-    expect(select.selectedIndex, 0);
+    nodeBind(select).bind('selectedIndex', new PathObserver(model, 'val'));
+    return new Future(() => expect(select.selectedIndex, 0));
   });
 
-  observeTest('Option.value', () {
+  test('Option.value', () {
     var option = testDiv.append(new OptionElement());
     var model = toObservable({'x': 42});
-    nodeBind(option).bind('value', model, 'x');
+    nodeBind(option).bind('value', new PathObserver(model, 'x'));
     expect(option.value, '42');
 
     model['x'] = 'Hi';
     expect(option.value, '42');
-    performMicrotaskCheckpoint();
-    expect(option.value, 'Hi');
+    return new Future(() => expect(option.value, 'Hi'));
+  });
+
+  test('Option.value - oneTime', () {
+    var option = testDiv.append(new OptionElement());
+    nodeBind(option).bind('value', 42, oneTime: true);
+    expect(option.value, '42');
   });
 
-  observeTest('Select.value', () {
+  test('Select.value', () {
     var select = testDiv.append(new SelectElement());
     testDiv.append(select);
     var option0 = select.append(new OptionElement());
@@ -626,25 +703,26 @@ formBindings() {
       'selected': 'b'
     });
 
-    nodeBind(option0).bind('value', model, 'opt0');
-    nodeBind(option1).bind('value', model, 'opt1');
-    nodeBind(option2).bind('value', model, 'opt2');
+    nodeBind(option0).bind('value', new PathObserver(model, 'opt0'));
+    nodeBind(option1).bind('value', new PathObserver(model, 'opt1'));
+    nodeBind(option2).bind('value', new PathObserver(model, 'opt2'));
 
-    nodeBind(select).bind('value', model, 'selected');
-    performMicrotaskCheckpoint();
-    expect(select.value, 'b');
+    nodeBind(select).bind('value', new PathObserver(model, 'selected'));
+    return new Future(() {
+      expect(select.value, 'b');
 
-    select.value = 'c';
-    dispatchEvent('change', select);
-    expect(model['selected'], 'c');
+      select.value = 'c';
+      dispatchEvent('change', select);
+      expect(model['selected'], 'c');
 
-    model['opt2'] = 'X';
-    performMicrotaskCheckpoint();
-    expect(select.value, 'X');
-    expect(model['selected'], 'X');
+      model['opt2'] = 'X';
+    }).then(endOfMicrotask).then((_) {
+      expect(select.value, 'X');
+      expect(model['selected'], 'X');
 
-    model['selected'] = 'a';
-    performMicrotaskCheckpoint();
-    expect(select.value, 'a');
+      model['selected'] = 'a';
+    }).then(endOfMicrotask).then((_) {
+      expect(select.value, 'a');
+    });
   });
 }