You better ask such specific Questions on the Mailing List or the irc channel (#catalyst, irc.perl.org).

There are multiple ways to test Catalyst apps, most people use the built in framework Catalyst::Test or Test::WWW::Mechanize::Catalyst.
Examples can be found in the countless tests included in the Catalyst distribution.

script/myapp_test.pl is just a command line interface for quick n dirty testing.