--- rake-0.9.2.2/test/test_rake_file_utils.rb.minitest	2011-12-19 12:25:09.032714303 +0900
+++ rake-0.9.2.2/test/test_rake_file_utils.rb	2011-12-19 13:41:55.851394829 +0900
@@ -208,6 +208,16 @@
     assert_equal '', err
   end
 
+  if ! defined?(assert_silent)
+    def assert_silent
+      out, err = capture_io do
+        yield
+      end
+      assert_equal '', out
+      assert_equal '', err
+    end
+  end
+
   def test_sh_verbose_flag_nil
     shellcommand