New expectation functions plus convert old tests to use these.

lib/unittest/map_matchers.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.
+
+/**
+ * Returns a matcher which matches objects containing the given [value].

[Bob Nystrom, 2012/06/01 18:22:23]

Might want to clarify that this is for maps, since it reads like it would work
on lists too.

[gram, 2012/06/01 22:22:00]

Done.

+ */
+IMatcher containsValue(value) => new _ContainsValue(value);
+
+class _ContainsValue extends Matcher {
+  final _value;
+
+  const _ContainsValue(this._value);
+
+  bool matches(item) => item.containsValue(_value);
+  IDescription describe(IDescription description) =>
+      description.add('contains value ').addDescriptionOf(_value);
+}
+
+/**
+ * Returns a matcher which matches maps containing the key-value pair
+ * with [key] => [value].
+ */
+IMatcher containsPair(key, value) =>
+    new _ContainsMapping(key, wrapMatcher(value));
+
+class _ContainsMapping extends Matcher {
+  final _key;
+  final IMatcher _valueMatcher;
+
+  const _ContainsMapping(this._key, IMatcher this._valueMatcher);
+
+  bool matches(item) =>
+      item.containsKey(_key) && _valueMatcher.matches(item[_key]);
+
+  IDescription describe(IDescription description) {
+    return description.add('contains pair ').addDescriptionOf(_key).
+          add(' => ').addDescriptionOf(_valueMatcher);
+  }
+
+  IDescription describeMismatch(item, IDescription mismatchDescription) {
+    if (!item.containsKey(_key)) {
+      return mismatchDescription.addDescriptionOf(item).
+          add("' doesn't contain key '").addDescriptionOf(_key);
+    } else {
+      return mismatchDescription.add(' contains key ').addDescriptionOf(_key).
+          add(' but with value ');
+      _valueMatcher.describeMismatch(item[_key], mismatchDescription);
+      return mismatchDescription;
+    }
+  }
+}