Improve matchers for enums defined by the analysis server API.

pkg/analysis_server/test/integration/integration_tests.dart

 // Copyright (c) 2014, 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 test.integration.analysis;
 
 import 'dart:async';
 import 'dart:collection';
 import 'dart:convert';
 import 'dart:io';
@@ skipping 270 matching lines @@
           mismatchDescription = mismatchDescription.add('; ').add(subDescription
               );
         }
         return mismatchDescription.add(')');
       });
     }
   }
 }
 
 /**
+ * Matcher that matches a String drawn from a limited set.
+ */
+class MatchesEnum extends Matcher {
+  /**
+   * Short description of the expected type.
+   */
+  final String description;
+
+  /**
+   * The set of enum values that are allowed.
+   */
+  final List<String> allowedValues;
+
+  const MatchesEnum(this.description, this.allowedValues);
+
+  @override
+  bool matches(item, Map matchState) {
+    return allowedValues.contains(item);
+  }
+
+  @override
+  Description describe(Description description) => description.add(
+      this.description);
+}
+
+/**
  * Matcher that matches a JSON object, with a given set of required and
  * optional fields, and their associated types (expressed as [Matcher]s).
  */
 class MatchesJsonObject extends _RecursiveMatcher {
   /**
    * Short description of the expected type.
    */
   final String description;
 
   /**
@@ skipping 389 matching lines @@
    */
   void _recordStdio(String line) {
     double elapsedTime = _time.elapsedTicks / _time.frequency;
     line = "$elapsedTime: $line";
     if (_debuggingStdio) {
       print(line);
     }
     _recordedStdio.add(line);
   }
 }