Log exceptions caught in polymer expressions

pkg/polymer_expressions/test/polymer_expressions_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.
+
+import 'dart:async';
+import 'dart:html'; // To indicate that this is an html test.
+
+import 'package:logging/logging.dart';
+import 'package:observe/observe.dart';
+import 'package:observe/src/microtask.dart';
+import 'package:polymer_expressions/polymer_expressions.dart';
+import 'package:unittest/unittest.dart';
+import 'package:unittest/html_config.dart';
+
+
+main() {
+  useHtmlConfiguration();
+  group('binding', () {
+    var stop = null;
+    var messages = [];
+    var model;
+    setUp(() {
+      stop = Logger.root.onRecord.listen((r) => messages.add(r));
+      model = new Foo();
+    });
+
+    tearDown(() {
+      stop.cancel();
+      stop = null;
+      messages = [];
+    });
+
+    observeTest('should update binding when data changes', () {
+      var binding = new PolymerExpressions()
+          .getBinding(model, 'name', null, null);
+      expect(binding.value, isNull);
+      model.name = "hi";
+      performMicrotaskCheckpoint();
+      expect(binding.value, 'hi');
+      expect(messages.length, 0);
+    });
+
+    observeTest('should log getter exceptions', () {
+      var binding = new PolymerExpressions()
+          .getBinding(model, 'readException', null, null);
+      expect(binding.value, isNull);
+      expect(messages.length, 1);
+      expect(messages[0].message,
+          "Error evaluating expression 'readException': exception (read)");
+    });
+
+    observeTest('should log setter exceptions', () {
+      var binding = new PolymerExpressions()
+          .getBinding(model, 'writeException', null, null);
+      expect(binding.value, '');
+      binding.value = 'hi';
+      performMicrotaskCheckpoint();
+      expect(messages.length, 1);
+      expect(messages[0].message,
+          "Error evaluating expression 'writeException': exception hi");
+    });
+  });
+}
+
+class Foo extends Object with ChangeNotifierMixin {
+  String _name;
+  String get name => _name;
+  void set name(String n) {
+    _name = notifyPropertyChange(const Symbol('name'), _name, n);
+  }
+
+  String get readException => throw "exception (read)";
+  void set readException(String value) => throw "exception $value";
+
+  String get writeException => '';
+  void set writeException(String value) => throw "exception $value";
+}
+
+
+/**
+ * This is a special kind of unit [test], that supports
+ * calling [performMicrotaskCheckpoint] during the test to pump events
+ * that original from observable objects.
+ */
+observeTest(name, testCase) => test(name, wrapMicrotask(testCase));
+
+/** The [solo_test] version of [observeTest]. */
+solo_observeTest(name, testCase) => solo_test(name, wrapMicrotask(testCase));