lib_MyService.pm

package MyService;
use IO::Socket::SSL;
use Mojo::Base 'Mojolicious';
use feature ':5.24';
use experimental qw(signatures refaliasing);
no warnings qw(experimental);

sub startup($app) {
    my $authorized = $app->routes->under('/')->to(cb => sub ($self) {
        if (my $basic = $self->req->headers->authorization) {
            # again, do somethind
            return 1;
        }

        $self->res->headers->www_authenticate("Basic realm=\"Authentication required\"");
        $self->res->code(401);
        $self->rendered;
        return;
    });

    $authorized->_generate_route(EVENT => '/myobject/:id')->to(cb => sub($self) {
        my $url     = $ENV{VERY_ENTERPRISE_HOST} . '/tasks/' . $self->param('id');
        my $headers = {
            Authorization  => 'Basic ' . encode_base64('foo:bar', ''),
            'Content-Type' => 'application/json;charset=utf-8',
        };

        eval { my $tx = $self->app->ua->post($url => $headers => json => { foo => 42 }); };
        say $@;
        $self->render(json => {});
    });
}

1;

t_test.pl

use feature ':5.24';

use Mojo::Base -strict;
use Test::More;
use Mojo::Server::Daemon;
use Mojolicious::Lite;
use Test::Mojo;
use experimental qw(signatures refaliasing);
no warnings qw(experimental);
use lib 'lib';
use MIME::Base64;

# mock the 3rdparty service
my $authorized = app->routes->under('/very/enterprise')->to(cb => sub ($self) {
    if (my $basic = $self->req->headers->authorization) {
        # do something
        return 1;
    }

    $self->res->headers->www_authenticate("Basic realm=\"Authentication required\"");
    $self->res->code(401);
    $self->rendered;
    return;
});

$authorized->any('/:route/:id')->to(cb => sub ($c) {
    $c->res->headers->append('X-ROUTE'   => $c->param('route'));
    $c->res->headers->append('X-METHOD'  => $c->method);
    $c->res->headers->append('X-TASK-ID' => $c->param('id'));
    $c->render(json => $c->req->json);
});

my $daemon = Mojo::Server::Daemon->new(app => app, listen => ['http://127.0.0.1'])
           ->start;
my $port   = Mojo::IOLoop->acceptor($daemon->acceptors->[0])->port;

$ENV{VERY_ENTERPRISE_HOST} = "http://127.0.0.1:$port/very/enterprise";

# now use our own service and start testing
my $t   = Test::Mojo->new('MyService');
$t->app->ua->ioloop(Mojo::IOLoop->singleton);

say my $url = $t->ua->server->url->userinfo('very:secret')->path('/myobject/1');

# acknowledge
my $tx = $t->ua->build_tx(EVENT => $url => json => { payload => 42 });
$t->request_ok($tx)->status_is(200);