Unit test changes:

pkg/unittest/lib/src/expect.dart

Index: pkg/unittest/lib/src/expect.dart
===================================================================
--- pkg/unittest/lib/src/expect.dart	(revision 19164)
+++ pkg/unittest/lib/src/expect.dart	(working copy)
@@ -4,6 +4,18 @@
 
 part of matcher;
 
+/** The objects thrown by the default failure handler. */
+class TestFailure {
+  String _message;
+
+  get message => _message;
+  set message(String value) => _message = value;
+
+  TestFailure(String message) : _message = message;
+
+  String toString() => _message;
+}
+
 /**
  * Some matchers, like those for Futures and exception testing,
  * can fail in asynchronous sections, and throw exceptions.
@@ -24,8 +36,8 @@
  * [matcher] can be a value in which case it will be wrapped in an
  * [equals] matcher.
  *
- * If the assertion fails, then the default behavior is to throw an
- * [ExpectException], but this behavior can be changed by calling
+ * If the assertion fails, then the default behavior is to throw a
+ * [TestFailure], but this behavior can be changed by calling
  * [configureExpectFailureHandler] and providing an alternative handler that
  * implements the [IFailureHandler] interface. It is also possible to
  * pass a [failureHandler] to [expect] as a final parameter for fine-
@@ -75,7 +87,7 @@
 // The handler for failed asserts.
 FailureHandler _assertFailureHandler = null;
 
-// The default failure handler that throws ExpectExceptions.
+// The default failure handler that throws [TestFailure]s.
 class DefaultFailureHandler implements FailureHandler {
   DefaultFailureHandler() {
     if (_assertErrorFormatter == null) {
@@ -83,7 +95,7 @@
     }
   }
   void fail(String reason) {
-    throw new ExpectException(reason);
+    throw new TestFailure(reason);
   }
   void failMatch(actual, Matcher matcher, String reason,
       MatchState matchState, bool verbose) {
@@ -95,7 +107,7 @@
  * Changes or resets to the default the failure handler for expect()
  * [handler] is a reference to the new handler; if this is omitted
  * or null then the failure handler is reset to the default, which
- * throws [ExpectExceptions] on [expect] assertion failures.
+ * throws [TestFailure]s on [expect] assertion failures.
  */
 void configureExpectFailureHandler([FailureHandler handler = null]) {
   if (handler == null) {