Improved error messages from unittest.

pkg/unittest/lib/src/iterable_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 matcher;
 
 /**
  * Returns a matcher which matches [Iterable]s in which all elements
  * match the given [matcher].
  */
@@ skipping 24 matching lines @@
   }
 
   Description describe(Description description) =>
       description.add('every element ').addDescriptionOf(_matcher);
 
   Description describeMismatch(item, Description mismatchDescription,
                                MatchState matchState, bool verbose) {
     if (matchState.state != null) {
       var index = matchState.state['index'];
       var element = matchState.state['element'];
-      mismatchDescription.add('position $index ');
+      mismatchDescription.add('at position $index ');
       return _matcher.describeMismatch(element, mismatchDescription,
             matchState.state['state'], verbose);
     }
     return super.describeMismatch(item, mismatchDescription,
           matchState, verbose);
   }
 }
 
 /**
  * Returns a matcher which matches [Iterable]s in which at least one
@@ skipping 32 matching lines @@
 
   bool matches(item, MatchState matchState) =>
       (item is Iterable) && _matcher.matches(item, matchState);
 
   Description describe(Description description) =>
       description.add('equals ').addDescriptionOf(_expected).add(' ordered');
 
   Description describeMismatch(item, Description mismatchDescription,
                                MatchState matchState, bool verbose) {
     if (item is !Iterable) {
-      return mismatchDescription.add('not an Iterable');
+      return mismatchDescription.add('is not an Iterable');
     } else {
       return _matcher.describeMismatch(item, mismatchDescription,
           matchState, verbose);
     }
   }
 }
 /**
  * Returns a matcher which matches [Iterable]s that have the same
  * length and the same elements as [expected], but not necessarily in
  * the same order. Note that this is O(n^2) so should only be used on
@@ skipping 114 matching lines @@
     }
     return true;
   }
     
   Description describe(Description description) =>
       description.add('pairwise $_description ').addDescriptionOf(_expected);
 
   Description describeMismatch(item, Description mismatchDescription,
                                MatchState matchState, bool verbose) {
     if (item is !Iterable) {
-      return mismatchDescription.add('not an Iterable');
+      return mismatchDescription.add('is not an Iterable');
     } else if (item.length != _expected.length) {
       return mismatchDescription.
-          add('length was ${item.length} instead of ${_expected.length}');
+          add('has length ${item.length} instead of ${_expected.length}');
     } else {
       return mismatchDescription.
+          add('has ').
           addDescriptionOf(matchState.state["actual"]).
-          add(' not $_description ').
+          add(' which is not $_description ').
           addDescriptionOf(matchState.state["expected"]).
           add(' at position ${matchState.state["index"]}');
     }
   }
 }