Improved error messages for type mismatches.

pkg/unittest/lib/src/core_matchers.dart

Index: pkg/unittest/lib/src/core_matchers.dart
===================================================================
--- pkg/unittest/lib/src/core_matchers.dart	(revision 21707)
+++ pkg/unittest/lib/src/core_matchers.dart	(working copy)
@@ -177,9 +177,8 @@
         var aType = typeName(actual);
         var includeTypes = eType != aType;
         // If we have recursed, show the expected value too; if not,
-        // 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) {
+        // expect() will show it for us.
+        if (depth > 0) {
           reason.add('expected ');
           if (includeTypes) {
             reason.add(eType).add(':');
@@ -191,6 +190,9 @@
           reason.add(aType).add(':');
         }
         reason.addDescriptionOf(actual);
+        if (includeTypes && depth == 0) {
+          reason.add(' (not type ').add(eType).add(')');
+        }
       }
     }
     if (reason != null && location.length > 0) {