render_spec.pl

# for Amon2
# spy on render method                                                    
sub render_spec {                                                                    
    my ($cb, $req, $spec) = @_;                                                        

    my $template;                                                                           
    my $param;                                                                              
    no warnings qw/redefine once/;                                                          
    my $render = *Amon2::Web::render;
    # for capture arguments of render method
    local *MyApp::Web::render = sub {
        (undef, $template, $param) = @_;                                                    
        $render->(@_);                                                                      
    };                                                                                      
    my $res = $cb->($req);                                                                  
    return $spec->($res, $template, $param);                                           
}

sample.t

subtest "/my/ render user name" => sub {
    my $app = Plack::Util::load_psgi 'app.psgi';
    test_psgi                                                                               
        app => $app,                                                                        
        client => sub {                                                                     
            my $cb = shift;                                                                 
            my $req = create_request(                                                       
                method  => 'GET',                                                           
                url     => "http://localhost/my/",                                    
            );                                                                             
            render_spec $cb, $req => sub {                                           
                my ($res, $template, $param) = @_;                                          
                is $res->code, 200;                                       
                is $template, 'tmpl/my/index.html';                                  
                is_deeply $param, { name => "koba04" };
            };
        };
};