Changes to how we handle fancy stacks:

pkg/unittest/lib/src/config.dart

Index: pkg/unittest/lib/src/config.dart
===================================================================
--- pkg/unittest/lib/src/config.dart	(revision 26205)
+++ pkg/unittest/lib/src/config.dart	(working copy)
@@ -55,7 +55,7 @@
 
   // If stopTestOnExpectFailure is false, we need to capture failures, which
   // we do with this List.
-  final _testLogBuffer = <Pair<String, Trace>>[];
+  final _testLogBuffer = <Pair<String, String>>[];

[nweiz, 2013/08/15 23:03:25]

Trace implements StackTrace, so you can make this a Pair<String, StackTrace> and
avoid converting to a string until you actually need a string representation.

[gram, 2013/08/16 16:56:45]

Done.

[gram, 2013/08/16 16:56:45]

Done.

 
   /**
    * The constructor sets up a failure handler for [expect] that redirects
@@ -72,6 +72,7 @@
    * asynchronously and that the process should wait until they are done.
    */
   void onInit() {
+    formatStacks = false;
     _receivePort = new ReceivePort();
     _postMessage('unittest-suite-wait-for-done');
   }
@@ -154,8 +155,9 @@
       try {
         throw '';
       } catch (_, stack) {
-        _testLogBuffer.add(
-            new Pair<String, Trace>(reason, new Trace.from(stack)));
+        var trace = _getTrace(stack);
+        if (trace == null) trace = stack;
+        _testLogBuffer.add(new Pair<String, String>(reason, trace.toString()));

[nweiz, 2013/08/15 23:03:25]

Why are you eagerly converting the stack trace to a string rather than just
making it a Pair<String, StackTrace>?

[gram, 2013/08/16 16:56:45]

Because I didn't realize Trace <- StackTrace. :-)

       }
     }
   }