Added hasProperty matcher.

pkg/unittest/test/mirror_matchers_test.dart

+// Copyright (c) 2012, 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:collection';
+
+import 'package:unittest/unittest.dart';
+import 'package:unittest/mirror_matchers.dart';
+
+import 'test_common.dart';
+import 'test_utils.dart';
+
+void main() {
+
+  initUtils();
+
+  test('hasProperty', () {
+    var foo = [3];
+    shouldPass(foo, hasProperty('length', 1));
+    shouldFail(foo, hasProperty('foo'), 'Expected: has property "foo" '
+        'Actual: [3] '
+        'Which: has no property named "foo"');
+    shouldFail(foo, hasProperty('length', 2),
+        'Expected: has property "length" which matches <2> '
+        'Actual: [3] '
+        'Which: has property "length" with value <1>');
+  });
+}