Log exceptions caught in polymer expressions

pkg/polymer_expressions/test/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 bindings_test;
 
 import 'dart:html';
+
+import 'package:logging/logging.dart';
 import 'package:mdv/mdv.dart' as mdv;
 import 'package:observe/observe.dart';
 import 'package:observe/src/microtask.dart';
 import 'package:polymer_expressions/polymer_expressions.dart';
 import 'package:unittest/html_config.dart';
 import 'package:unittest/unittest.dart';
 
 main() {
   mdv.initialize();
   useHtmlConfiguration();
 
-  group('cursor position tests', () {
+  group('bindings', () {
+    var stop = null;
+    var messages = [];
     var testDiv;
     setUp(() {
+      stop = Logger.root.onRecord.listen((r) => messages.add(r));
       document.body.append(testDiv = new DivElement());
     });
 
     tearDown(() {
       testDiv.remove();
       testDiv = null;
+      stop.cancel();
+      stop = null;
+      messages = [];
     });
 
-    test('cursor position test', wrapMicrotask(() {
+    observeTest('should update binding when data changes', () {
+      var model = new NotifyModel();
+      var binding = new PolymerExpressions()
+          .getBinding(model, 'x', null, null);
+      expect(binding.value, isNull);
+      model.x = "hi";
+      performMicrotaskCheckpoint();
+      expect(binding.value, 'hi');
+      expect(messages.length, 0);
+    });
+
+    observeTest('should update text content when data changes', () {
+      var model = new NotifyModel('abcde');
+      var template = new Element.html(
+          '<template><span>{{x}}</span></template>');
+      testDiv.append(template.createInstance(model, new PolymerExpressions()));
+
+      performMicrotaskCheckpoint();
+      var el = testDiv.query("span");
+      expect(el.text, 'abcde');
+      expect(model.x, 'abcde');
+      model.x = '___';
+
+      performMicrotaskCheckpoint();
+      expect(model.x, '___');
+      expect(el.text, '___');
+    });
+
+    observeTest('should log eval exceptions', () {
+      var model = new NotifyModel('abcde');
+      var template = new Element.html(
+          '<template><span>{{foo}}</span></template>');
+      testDiv.append(template.createInstance(model, new PolymerExpressions()));
+      performMicrotaskCheckpoint();
+      expect(messages.length, 1);
+      expect(messages[0].message,
+          "Error evaluating expression 'foo': variable 'foo' not found");
+    });
+
+    observeTest('should preserve the cursor position', () {
       var model = new NotifyModel('abcde');
       var template = new Element.html(
           '<template><input id="i1" value={{x}}></template>');
       testDiv.append(template.createInstance(model, new PolymerExpressions()));
 
       performMicrotaskCheckpoint();
       var el = testDiv.query("#i1");
       var subscription = el.onInput.listen(expectAsync1((_) {
         performMicrotaskCheckpoint();
       }, count: 1));
@@ skipping 20 matching lines @@
       el.dispatchEvent(new Event('input'));
       expect(model.x, 'abc de');
       expect(el.value, 'abc de');
 
       // But propagating observable values through reassign the value and
       // selection will be preserved.
       expect(el.selectionStart, 4);
       expect(el.selectionEnd, 4);
 
       subscription.cancel();
-    }));
+    });
   });
 }
 
 @reflectable
 class NotifyModel extends ChangeNotifier {
   var _x;
   NotifyModel([this._x]);
 
   get x => _x;
   set x(value) {
-    _x = notifyPropertyChange(const Symbol('x'), _x, value);
+    _x = notifyPropertyChange(#x, _x, value);
   }
 }
+
+observeTest(name, testCase) => test(name, wrapMicrotask(testCase));