silences stderr to prevent an expected error message in the test suite from being echoed

railties/test/generators/app_generator_test.rb

@@ -66,8 +66,7 @@ def test_invalid_application_name_is_fixed
   end
 
   def test_application_new_exits_with_non_zero_code_on_invalid_application_name
-    # TODO: Suppress the output of this (it's because of a Thor::Error)
-    `rails new test`
+    silence_stderr { `rails new test` }
     assert_equal false, $?.success?
   end