pkg/unittest: tweaks to mock, re-enabled most tests

pkg/unittest/lib/src/core_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.
 
 part of unittest.matcher;
 
 /**
  * Returns a matcher that matches empty strings, maps or iterables
  * (including collections).
  */
@@ skipping 282 matching lines @@
         buff.write('^\n Differ at offset $start');
       }
 
       return mismatchDescription.replace(buff.toString());
     }
   }
 
   static String _escape(String s) =>
       s.replaceAll('\n', '\\n').replaceAll('\r', '\\r').replaceAll('\t', '\\t');
 
-  static String _writeLeading(StringBuffer buff, String s, int start) {
+  static void _writeLeading(StringBuffer buff, String s, int start) {
     if (start > 10) {
       buff.write('... ');
       buff.write(s.substring(start - 10, start));
     } else {
       buff.write(s.substring(0, start));
     }
   }
 
-  static String _writeTrailing(StringBuffer buff, String s, int start) {
+  static void _writeTrailing(StringBuffer buff, String s, int start) {
     if (start + 10 > s.length) {
       buff.write(s.substring(start));
     } else {
       buff.write(s.substring(start, start + 10));
       buff.write(' ...');
     }
   }
 }
 
 /** A matcher that matches any value. */
@@ skipping 562 matching lines @@
         addDescriptionOf(matchState['feature']);
     var innerDescription = new StringDescription();
     _matcher.describeMismatch(matchState['feature'], innerDescription,
         matchState['state'], verbose);
     if (innerDescription.length > 0) {
       mismatchDescription.add(' which ').add(innerDescription.toString());
     }
     return mismatchDescription;
   }
 }