README.md in seatbelt-0.3.1 vs README.md in seatbelt-0.4.0

@@ -90,10 +90,10 @@
       this_sends_an_email
     end
   end
 
   def test_crosscheck
-    assert_no_mail do
+    refute_mail do
       this_should_not_send_an_email
     end
   end
 
   def test_other_crosscheck