More fixes to unittest

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 matcher;
 
 /**
  * Returns a matcher that matches empty strings, maps or collections.
  */
 const Matcher isEmpty = const _Empty();
@@ skipping 272 matching lines @@
   bool matches(item, MatchState matchState) {
     if (item is Future) {
       var done = wrapAsync((fn) => fn());
 
       // Queue up an asynchronous expectation that validates when the future
       // completes.
       item.then((value) {
         done(() => expect(false, isTrue, reason:
             "Expected future to fail, but succeeded with '$value'."));
       }, onError: (e) {
-        var reason;
-        if (e.stackTrace != null) {
-          var stackTrace = e.stackTrace.toString();
-          stackTrace = "  ${stackTrace.replaceAll("\n", "\n  ")}";
-          reason = "Actual exception trace:\n$stackTrace";
-        }
-        done(() => expect(e.error, _matcher, reason: reason));
+        done(() {
+          if (_matcher == null) return;
+          var reason;
+          if (e.stackTrace != null) {
+            var stackTrace = e.stackTrace.toString();
+            stackTrace = "  ${stackTrace.replaceAll("\n", "\n  ")}";
+            reason = "Actual exception trace:\n$stackTrace";
+          }
+          expect(e.error, _matcher, reason: reason);
+        });
       });
 
       // It hasn't failed yet.
       return true;
     }
 
     try {
       item();
       return false;
     } catch (e, s) {
@@ skipping 367 matching lines @@
       description.add(_featureDescription).add(' ').addDescriptionOf(_matcher);
 
   Description describeMismatch(item, Description mismatchDescription,
                                MatchState matchState, bool verbose) {
     mismatchDescription.add(_featureName).add(' ');
     _matcher.describeMismatch(matchState.state['feature'], mismatchDescription,
         matchState.state['innerState'], verbose);
     return mismatchDescription;
   }
 }