use symbol literals instead of const ctor in packages

pkg/mdv/test/element_bindings_test.dart

 // Copyright (c) 2013, 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 node_bindings_test;
 
 import 'dart:async';
 import 'dart:html';
 import 'package:mdv/mdv.dart' as mdv;
 import 'package:observe/observe.dart';
 import 'package:unittest/html_config.dart';
 import 'package:unittest/unittest.dart';
 import 'mdv_test_utils.dart';
 
 // Note: this file ported from
 // https://github.com/toolkitchen/mdv/blob/master/tests/element_bindings.js
 
 main() {
   mdv.initialize();
   useHtmlConfiguration();
   group('Element Bindings', elementBindingTests);
 }
 
-sym(x) => new Symbol(x);
-
 observePath(obj, path) => new PathObserver(obj, path);
 
 elementBindingTests() {
   var testDiv;
 
   setUp(() {
     document.body.append(testDiv = new DivElement());
   });
 
   tearDown(() {
     testDiv.remove();
     testDiv = null;
   });
 
   observeTest('Text', () {
     var template = new Element.html('<template bind>{{a}} and {{b}}');
     testDiv.append(template);
     var model = toSymbolMap({'a': 1, 'b': 2});
     template.model = model;
     performMicrotaskCheckpoint();
     var text = testDiv.nodes[1];
     expect(text.text, '1 and 2');
 
-    model[sym('a')] = 3;
+    model[#a] = 3;
     performMicrotaskCheckpoint();
     expect(text.text, '3 and 2');
   });
 
   observeTest('SimpleBinding', () {
     var el = new DivElement();
     var model = toSymbolMap({'a': '1'});
     el.bind('foo', model, 'a');
     performMicrotaskCheckpoint();
     expect(el.attributes['foo'], '1');
 
-    model[sym('a')] = '2';
+    model[#a] = '2';
     performMicrotaskCheckpoint();
     expect(el.attributes['foo'], '2');
 
-    model[sym('a')] = 232.2;
+    model[#a] = 232.2;
     performMicrotaskCheckpoint();
     expect(el.attributes['foo'], '232.2');
 
-    model[sym('a')] = 232;
+    model[#a] = 232;
     performMicrotaskCheckpoint();
     expect(el.attributes['foo'], '232');
 
-    model[sym('a')] = null;
+    model[#a] = null;
     performMicrotaskCheckpoint();
     expect(el.attributes['foo'], '');
   });
 
   observeTest('SimpleBindingWithDashes', () {
     var el = new DivElement();
     var model = toSymbolMap({'a': '1'});
     el.bind('foo-bar', model, 'a');
     performMicrotaskCheckpoint();
     expect(el.attributes['foo-bar'], '1');
 
-    model[sym('a')] = '2';
+    model[#a] = '2';
     performMicrotaskCheckpoint();
     expect(el.attributes['foo-bar'], '2');
   });
 
   observeTest('SimpleBindingWithComment', () {
     var el = new DivElement();
     el.innerHtml = '<!-- Comment -->';
     var model = toSymbolMap({'a': '1'});
     el.bind('foo-bar', model, 'a');
     performMicrotaskCheckpoint();
     expect(el.attributes['foo-bar'], '1');
 
-    model[sym('a')] = '2';
+    model[#a] = '2';
     performMicrotaskCheckpoint();
     expect(el.attributes['foo-bar'], '2');
   });
 
   observeTest('PlaceHolderBindingText', () {
     var model = toSymbolMap({
       'adj': 'cruel',
       'noun': 'world'
     });
 
     var el = new DivElement();
     el.text = 'dummy';
     el.nodes.first.text = 'Hello {{ adj }} {{noun}}!';
     var template = new Element.html('<template bind>');
     template.content.append(el);
     testDiv.append(template);
     template.model = model;
 
     performMicrotaskCheckpoint();
     el = testDiv.nodes[1].nodes.first;
     expect(el.text, 'Hello cruel world!');
 
-    model[sym('adj')] = 'happy';
+    model[#adj] = 'happy';
     performMicrotaskCheckpoint();
     expect(el.text, 'Hello happy world!');
   });
 
   observeTest('InputElementTextBinding', () {
     var model = toSymbolMap({'val': 'ping'});
 
     var el = new InputElement();
     el.bind('value', model, 'val');
     performMicrotaskCheckpoint();
     expect(el.value, 'ping');
 
     el.value = 'pong';
     dispatchEvent('input', el);
-    expect(model[sym('val')], 'pong');
+    expect(model[#val], 'pong');
 
     // Try a deep path.
     model = toSymbolMap({'a': {'b': {'c': 'ping'}}});
 
     el.bind('value', model, 'a.b.c');
     performMicrotaskCheckpoint();
     expect(el.value, 'ping');
 
     el.value = 'pong';
     dispatchEvent('input', el);
     expect(observePath(model, 'a.b.c').value, 'pong');
 
     // Start with the model property being absent.
-    model[sym('a')][sym('b')].remove(sym('c'));
+    model[#a][#b].remove(#c);
     performMicrotaskCheckpoint();
     expect(el.value, '');
 
     el.value = 'pong';
     dispatchEvent('input', el);
     expect(observePath(model, 'a.b.c').value, 'pong');
     performMicrotaskCheckpoint();
 
     // Model property unreachable (and unsettable).
-    model[sym('a')].remove(sym('b'));
+    model[#a].remove(#b);
     performMicrotaskCheckpoint();
     expect(el.value, '');
 
     el.value = 'pong';
     dispatchEvent('input', el);
     expect(observePath(model, 'a.b.c').value, null);
   });
 
   observeTest('InputElementCheckbox', () {
     var model = toSymbolMap({'val': true});
 
     var el = new InputElement();
     testDiv.append(el);
     el.type = 'checkbox';
     el.bind('checked', model, 'val');
     performMicrotaskCheckpoint();
     expect(el.checked, true);
 
-    model[sym('val')] = false;
+    model[#val] = false;
     performMicrotaskCheckpoint();
     expect(el.checked, false);
 
     el.click();
-    expect(model[sym('val')], true);
+    expect(model[#val], true);
 
     el.click();
-    expect(model[sym('val')], false);
+    expect(model[#val], false);
 
     el.onClick.listen((_) {
-      expect(model[sym('val')], true);
+      expect(model[#val], true);
     });
     el.onChange.listen((_) {
-      expect(model[sym('val')], true);
+      expect(model[#val], true);
     });
 
     el.dispatchEvent(new MouseEvent('click', view: window));
   });
 
   observeTest('InputElementCheckbox - binding updated on click', () {
     var model = toSymbolMap({'val': true});
 
     var el = new InputElement();
     testDiv.append(el);
     el.type = 'checkbox';
     el.bind('checked', model, 'val');
     performMicrotaskCheckpoint();
     expect(el.checked, true);
 
     el.onClick.listen((_) {
-      expect(model[sym('val')], false);
+      expect(model[#val], false);
     });
 
     el.dispatchEvent(new MouseEvent('click', view: window));
   });
 
   observeTest('InputElementCheckbox - binding updated on change', () {
     var model = toSymbolMap({'val': true});
 
     var el = new InputElement();
     testDiv.append(el);
     el.type = 'checkbox';
     el.bind('checked', model, 'val');
     performMicrotaskCheckpoint();
     expect(el.checked, true);
 
     el.onChange.listen((_) {
-      expect(model[sym('val')], false);
+      expect(model[#val], false);
     });
 
     el.dispatchEvent(new MouseEvent('click', view: window));
    });
 
   observeTest('InputElementRadio', () {
     var model = toSymbolMap({'val1': true, 'val2': false, 'val3': false,
         'val4': true});
     var RADIO_GROUP_NAME = 'observeTest';
 
@@ skipping 22 matching lines @@
     el4.type = 'radio';
     el4.name = 'othergroup';
     el4.bind('checked', model, 'val4');
 
     performMicrotaskCheckpoint();
     expect(el1.checked, true);
     expect(el2.checked, false);
     expect(el3.checked, false);
     expect(el4.checked, true);
 
-    model[sym('val1')] = false;
-    model[sym('val2')] = 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[sym('val1')], true);
-    expect(model[sym('val2')], false);
-    expect(model[sym('val3')], false);
-    expect(model[sym('val4')], true);
+    expect(model[#val1], true);
+    expect(model[#val2], false);
+    expect(model[#val3], false);
+    expect(model[#val4], true);
 
     el3.checked = true;
     dispatchEvent('change', el3);
-    expect(model[sym('val1')], false);
-    expect(model[sym('val2')], false);
-    expect(model[sym('val3')], true);
-    expect(model[sym('val4')], true);
+    expect(model[#val1], false);
+    expect(model[#val2], false);
+    expect(model[#val3], true);
+    expect(model[#val4], true);
   });
 
   observeTest('InputElementRadioMultipleForms', () {
     var model = toSymbolMap({'val1': true, 'val2': false, 'val3': false,
         'val4': true});
     var RADIO_GROUP_NAME = 'observeTest';
 
     var form1 = new FormElement();
     testDiv.append(form1);
     var form2 = new FormElement();
@@ skipping 24 matching lines @@
     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[sym('val1')], false);
-    expect(model[sym('val2')], true);
+    expect(model[#val1], false);
+    expect(model[#val2], true);
 
     // Radio buttons in form2 should be unaffected
-    expect(model[sym('val3')], false);
-    expect(model[sym('val4')], true);
+    expect(model[#val3], false);
+    expect(model[#val4], true);
 
     el3.checked = true;
     dispatchEvent('change', el3);
-    expect(model[sym('val3')], true);
-    expect(model[sym('val4')], false);
+    expect(model[#val3], true);
+    expect(model[#val4], false);
 
     // Radio buttons in form1 should be unaffected
-    expect(model[sym('val1')], false);
-    expect(model[sym('val2')], true);
+    expect(model[#val1], false);
+    expect(model[#val2], true);
   });
 
   observeTest('BindToChecked', () {
     var div = new DivElement();
     testDiv.append(div);
     var child = new DivElement();
     div.append(child);
     var input = new InputElement();
     child.append(input);
     input.type = 'checkbox';
 
     var model = toSymbolMap({'a': {'b': false}});
     input.bind('checked', model, 'a.b');
 
     input.click();
-    expect(model[sym('a')][sym('b')], true);
+    expect(model[#a][#b], true);
 
     input.click();
-    expect(model[sym('a')][sym('b')], false);
+    expect(model[#a][#b], false);
   });
 
   observeTest('Select selectedIndex', () {
     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());
 
     var model = toSymbolMap({'val': 2});
 
     select.bind('selectedIndex', model, 'val');
     performMicrotaskCheckpoint();
     expect(select.selectedIndex, 2);
 
     select.selectedIndex = 1;
     dispatchEvent('change', select);
-    expect(model[sym('val')], 1);
+    expect(model[#val], 1);
   });
 
   observeTest('MultipleReferences', () {
     var el = new DivElement();
     var template = new Element.html('<template bind>');
     template.content.append(el);
     testDiv.append(template);
 
     var model = toSymbolMap({'foo': 'bar'});
     el.attributes['foo'] = '{{foo}} {{foo}}';
     template.model = model;
 
     performMicrotaskCheckpoint();
     el = testDiv.nodes[1];
     expect(el.attributes['foo'], 'bar bar');
   });
 }