Catalyst :: Test является подклассом LWP :: UserAgent. Ниже следует дать вам правильную идею:
#!/usr/bin/env perl
use warnings;
use strict;
use Test::More;
use Catalyst::Test 'MyApp';
use HTTP::Request::Common;
use JSON::Any; # or whatever json module you usually use
my $data = 'some_json_data_here';
my $res = request(
POST '/some_path',
Content_Type => 'text/xml',
Content => $data,
);
my $content = json_decode($res->content); # or whatever, can't remember the interface.
my $expected = "some_data";
is_deeply ( $content, $expected);