Unit test improvements:

pkg/unittest/test/matchers_test.dart

Index: pkg/unittest/test/matchers_test.dart
===================================================================
--- pkg/unittest/test/matchers_test.dart	(revision 18358)
+++ pkg/unittest/test/matchers_test.dart	(working copy)
@@ -128,6 +128,8 @@
       shouldFail(doesNotThrow, throws,
         "Expected: throws an exception but: no exception.");
       shouldPass(doesThrow, throws);
+      shouldFail(true, throws,
+          "Expected: throws an exception but: not a Function or Future.");
     });
 
     test('throwsA', () {
@@ -243,6 +245,15 @@
         "but: was <[0, 0]> with length of <2>.");
       shouldPass(b, hasLength(2));
     });
+
+    test('type mismatch', () {
+      var a = new DateTime.utc(2000);
+      var b = a.toString();
+      shouldFail(a, equals(b),
+          "Expected: '2000-01-01 00:00:00.000Z' "
+          "but: expected String:'2000-01-01 00:00:00.000Z' "
+          "but was DateTime:<2000-01-01 00:00:00.000Z>.");
+    });
   });
 
   group('Numeric Matchers', () {