I found the documentation of this module and the diagnostics less than helpful. An apparent bug triggered by CGI::Application::Dispatch has been a significant time sink for me ( rt.cpan.org/Public/Bug/Display.html?i... ).
My experience has been that this module takes a fair of wrestling with.
Apache::TestRequest -- it's the kind of module you've written many times, but don't have to any more now it's on CPAN. Fully documented, allows rapid development of tests against the Apache configuration and responses.
Sadly, hasn't been ported to run on a modern (2.*) Apache mod_perl server.
Comes as part of an impressive looking Apache::Test suite.
This is a very useful module that integrates nicely with the standard Test::Harness/Test::More way of doing things. It takes care of starting/stopping a special Apache instance and managing requests/responses. Your test scripts can very easily fire off requests and check that each response has the right status code, headers and content.
Works for testing Apache handlers and CGI scripts written in any language (obviously including mod_perl).