在 Dancer2 应用程序中存根/模拟服务

Question

通常，我有一个与此类似的设置：

#!/usr/bin/env perl
package Demo;
use Dancer2;
use Moose;

sub get($self, $params) {
    my $whatever = ...; # connect with db and do stuff
    return $whatever;
}

my $service = Demo->new();

sub make_web_friendly($param) { # no $self, here!
    return "Hello $param!";
}
 
get '/' => sub {
    my $response = $service->get(query_parameters);
    return make_web_friendly($response);
};
 
start;

这样，我可以很好地分离关注点，并且我的服务可以测试，而无需通过 Plack::Test 处理虚假的 Web 请求；

然而，每当我测试请求时，我总是也会测试服务，这违背了这种分离。

我想为 Plack 测试提供一个模拟服务答案的存根服务。因此（我假设）我要么可以以某种方式使 get 操作 $self 感知，要么必须将模拟的服务传递给 Plack。

# this is put together to showcase the principle, it does not work

package Stub {
    use Moose;
    use Test::More;
    use Data::Dumper;

    sub get($self, $params) {
        diag "I received:" . Dumper($params);
        return "Bianca!";
    }
}

my $app = Demo->to_app;
my $test = Plack::Test->create($app);
my $stub = Stub->new();
$test->service($stub);
my $request  = HTTP::Request->new( GET => '/' );
my $response = $test->request($request);
is $response, 'Hello, Bianca', 'Bianca was here';

我怎样才能实现（类似的）这个目标？