Unit test improvements:

pkg/unittest/lib/src/core_matchers.dart

Index: pkg/unittest/lib/src/core_matchers.dart
===================================================================
--- pkg/unittest/lib/src/core_matchers.dart	(revision 18358)
+++ pkg/unittest/lib/src/core_matchers.dart	(working copy)
@@ -172,15 +172,23 @@
           }
         }
       } else {
+        reason = new StringDescription();
+        var includeTypes = expected.runtimeType != actual.runtimeType;
         // If we have recursed, show the expected value too; if not,
-        // expect() will show it for us.
-        reason = new StringDescription();
-        if (depth > 1) {
-          reason.add('expected ').addDescriptionOf(expected).add(' but was ').
-              addDescriptionOf(actual);
-        } else {
-          reason.add('was ').addDescriptionOf(actual);
+        // expect() will show it for us. As expect will not show type
+        // mismatches at the top level we handle those here too.
+        if (includeTypes || depth > 1) {
+          reason.add('expected ');
+          if (includeTypes) {
+            reason..add(expected.runtimeType).add(':');
+          }
+          reason.addDescriptionOf(expected).add(' but ');
         }
+        reason.add('was ');
+        if (includeTypes) {
+          reason..add(actual.runtimeType).add(':');
+        }
+        reason.addDescriptionOf(actual);
       }
     }
     if (reason != null && location.length > 0) {
@@ -320,6 +328,8 @@
 
       // It hasn't failed yet.
       return true;
+    } else if (item is! Function) {
+      return false;

[Siggi Cherem (dart-lang), 2013/02/12 20:48:51]

nit: given that this is fast-exit code, it might be nice to see it upfront:

bool matches(item, ...) {
  if (item is! Function && item is! Future) return false;
  if (item is Future) {
    ...
  }

[gram, 2013/02/12 20:59:30]

Done.

     }
 
     try {
@@ -350,7 +360,9 @@
   Description describeMismatch(item, Description mismatchDescription,
                                MatchState matchState,
                                bool verbose) {
-    if (_matcher == null ||  matchState.state == null) {
+    if (item is! Function && item is! Future) {
+      return mismatchDescription.add(' not a Function or Future');
+    } else if (_matcher == null ||  matchState.state == null) {
       return mismatchDescription.add(' no exception');
     } else {
       mismatchDescription.