Added hasProperty matcher.

pkg/unittest/lib/mirror_matchers.dart

Index: pkg/unittest/lib/mirror_matchers.dart
===================================================================
--- pkg/unittest/lib/mirror_matchers.dart	(revision 0)
+++ pkg/unittest/lib/mirror_matchers.dart	(revision 0)
@@ -0,0 +1,92 @@
+// 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.
+/**
+ * The mirror matchers library provides some additional matchers that
+ * make use of dart:mirrors.
+ *
+ * ## Installing ##
+ *
+ * Use [pub][] to install this package. Add the following to your `pubspec.yaml`
+ * file.
+ *
+ *     dependencies:
+ *       unittest: any
+ *
+ * Then run `pub install`.
+ *
+ * Import this into your Dart code with:
+ *
+ *     import 'package:unittest/mirror_matchers.dart';
+ *
+ * For more information, see the [unittest package on pub.dartlang.org].
+ * (http://pub.dartlang.org/packages/unittest).
+ *
+ * [pub]: http://pub.dartlang.org
+ * [pkg]: http://pub.dartlang.org/packages/mirror_matchers
+ */
+library mirror_matchers;
+
+import 'dart:async';
+import 'dart:mirrors';
+import 'package:meta/meta.dart';
+
+import 'matcher.dart';
+
+/**
+ * Returns a matcher that checks if a class instance has a property
+ * with name [name], and optionally, if that property in turn satisfies
+ * a [matcher].
+ */
+Matcher hasProperty(String name, [matcher]) =>
+  new _HasProperty(name, matcher == null ? null : wrapMatcher(matcher));
+
+class _HasProperty extends Matcher {
+  final String _name;
+  final Matcher _matcher;
+
+  const _HasProperty(this._name, [this._matcher]);
+
+  bool matches(item, Map matchState) {
+    var mirror = reflect(item);
+    var classMirror = mirror.type;
+    var symbol = new Symbol(_name);
+    if (!classMirror.getters.containsKey(symbol)) {
+      addStateInfo(matchState, {'reason': 'has no property named "$_name"'});
+      return false;
+    }
+    if (_matcher == null) return true;
+    var result = mirror.getField(symbol);
+    var resultMatches = _matcher.matches(result.reflectee, matchState);
+    if (!resultMatches) {
+      addStateInfo(matchState, {'value': result.reflectee});
+    }
+    return resultMatches;
+  }
+
+  Description describe(Description description) {
+    description.add('has property "$_name"');
+    if (_matcher != null) {
+      description.add(' which matches ').addDescriptionOf(_matcher);
+    }
+    return description;
+  }
+
+  Description describeMismatch(item, Description mismatchDescription,
+                               Map matchState, bool verbose) {
+    var reason = matchState == null ? null : matchState['reason'];
+    if (reason != null) {
+      mismatchDescription.add(reason);
+    } else {
+      mismatchDescription.add('has property "$_name" with value ').
+        addDescriptionOf(matchState['value']);
+      var innerDescription = new StringDescription();
+      _matcher.describeMismatch(matchState['value'], innerDescription,
+          matchState['state'], verbose);
+      if (innerDescription.length > 0) {
+        mismatchDescription.add(' which ').add(innerDescription.toString());
+      }
+    }
+    return mismatchDescription;
+  }
+}