gistfile1.PL

test_psgi
  app => Plack::App::Proxy->new(host => sub {
    my $env = shift;
    ($env->{PATH_INFO} =~ /^\/(.+)/);
  }),
  client => sub {
    my $cb = shift;
    my $req = HTTP::Request->new(GET => "http://localhost/http://www.google.com");
    my $res = $cb->($req);
    like $res->content, qr/Google Search/, "google";
  };