module for testing plack application warnings

 Plack::Middleware::Test::StashWarnings is a Plack middleware component to
 record warnings generated by your application so that you can test them to
 make sure your application complains about the right things.
 .
 The warnings generated by your application are available at a special URL
 (/__test_warnings), encoded with Storable/nfreeze. So using
 Test::WWW::Mechanize you can just get that URL and Storable/thaw its content.