test.go

package main
import (
	"fmt"
	"net/http"
	"net/http/httptest"
	"github.com/vulcand/oxy/forward"
	"github.com/vulcand/oxy/testutils"
	"strconv"
)


// Variables to identify the build
var (
	Version string
	Build string
)

func redirect(hello_string string) http.Handler {
	fn := func(w http.ResponseWriter, r *http.Request) {
		fwd, _ := forward.New()
		recorder := httptest.NewRecorder()

		// let us forward this request to another server
		r.URL = testutils.ParseURI("https://jsonplaceholder.typicode.com:443/posts/1")
		fwd.ServeHTTP(recorder, r)

		// yoda
		data := []byte(hello_string)

		// and set an additional one
		w.Header().Set("X-We-Modified-This", "Yup")

		// But the Content-Length might have been set already,
		// we should modify it by adding the length
		clen, _ := strconv.Atoi(r.Header.Get("Content-Length"))
		clen += len(data)
		r.Header.Set("Content-Length", strconv.Itoa(clen))

		// finally, write out our data and the original body
		w.Write(data)
		w.Write(recorder.Body.Bytes())

	}
	return http.HandlerFunc(fn)
}

func main() {
	fmt.Println("Version: ", Version)
	fmt.Println("Git commit hash: ", Build)

	redirect := redirect("To the hand you talk, because listening I'm not")
	
	s := &http.Server{
		Addr:           ":8080",
		Handler:        redirect,
	}
	s.ListenAndServe()
}

Exactly what are you trying to accomplish?