以下のように、Mojo::Server::Daemonで簡易なWebサーバを作ることができます。

sample.pl

use strict;
use warnings;
use utf8;
use Encode;
use Mojo::Server::Daemon;

my $daemon = Mojo::Server::Daemon->new(listen => ['http://*:8080']);
$daemon->unsubscribe('request');
$daemon->on(request => sub {
    my ($daemon, $tx) = @_;

    # Request
    my $method = $tx->req->method;
    my $path   = $tx->req->url->path;

    if ($path eq '/test.html') {
         $tx->res->code(200);
		  $tx->res->headers->content_type('text/html');
         $tx->res->body(encode_utf8('<html><head><title>テスト</title></head><body><h1>テスト</h1></body></html>'));

    }
	elsif ($path eq '/test.txt') {
         $tx->res->code(200);
         $tx->res->headers->content_type('text/plain');
         $tx->res->body(encode_utf8('テスト'));
    }
    else {
         $tx->res->code(404);
         $tx->res->body('Not Found');
    }

    # Resume transaction
    $tx->resume
});
$daemon->run;

Test::TCPを使えば、一時的にWebサーバを立ち上げてテストすることができます。

sample.pl

use strict;
use warnings;
use utf8;
use Encode;
use Mojo::Server::Daemon;
use Test::More;
use Test::TCP;
use Mojo::UserAgent;


test_tcp(
    client => sub {
        my $post = shift;

        my $url = 'http://localhost:'.$post;
        my $client = Mojo::UserAgent->new;

        my $tx = $client->get($url.'/test.html');
        if (my $res = $tx->success) {
            is decode_utf8($res->body), '<html><head><title>テスト</title></head><body><h1>テスト</h1></body></html>';
        }

        $tx = $client->get($url.'/test.txt');
        if (my $res = $tx->success) {
            is decode_utf8($res->body), 'テスト';
        }
    },
    server => sub {
        my $port = shift;
        my $daemon = build_server($port);
        $daemon->run;
    },
);


sub build_server {
    my ($port) = @_;

    my $daemon = Mojo::Server::Daemon->new(listen => ['http://*:'.$port]);
    $daemon->unsubscribe('request');
    $daemon->on(request => sub {
        my ($daemon, $tx) = @_;

        # Request
        my $method = $tx->req->method;
        my $path   = $tx->req->url->path;

        if ($path eq '/test.html') {
             $tx->res->code(200);
              $tx->res->headers->content_type('text/html');
             $tx->res->body(encode_utf8('<html><head><title>テスト</title></head><body><h1>テスト</h1></body></html>'));

        }
        elsif ($path eq '/test.txt') {
             $tx->res->code(200);
             $tx->res->headers->content_type('text/plain');
             $tx->res->body(encode_utf8('テスト'));
        }
        else {
             $tx->res->code(404);
             $tx->res->body('Not Found');
        }

        # Resume transaction
        $tx->resume
    });
    $daemon;
}

done_testing;