net/http/httputil: add package level examples

Change-Id: I5be18b68602a7ebb740cf05924236ce17e386e55
Reviewed-on: https://go-review.googlesource.com/17295
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

src/net/http/httputil/example_test.go

+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package httputil_test
+
+import (
+	"fmt"
+	"io/ioutil"
+	"log"
+	"net/http"
+	"net/http/httptest"
+	"net/http/httputil"
+	"net/url"
+	"strings"
+)
+
+func ExampleDumpRequest() {
+	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		dump, err := httputil.DumpRequest(r, true)
+		if err != nil {
+			http.Error(w, fmt.Sprint(err), http.StatusInternalServerError)
+			return
+		}
+
+		fmt.Fprintf(w, "%q", dump)
+	}))
+	defer ts.Close()
+
+	const body = "Go is a general-purpose language designed with systems programming in mind."
+	req, err := http.NewRequest("POST", ts.URL, strings.NewReader(body))
+	if err != nil {
+		log.Fatal(err)
+	}
+	req.Host = "www.example.org"
+	resp, err := http.DefaultClient.Do(req)
+	if err != nil {
+		log.Fatal(err)
+	}
+	defer resp.Body.Close()
+
+	b, err := ioutil.ReadAll(resp.Body)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	fmt.Printf("%s", b)
+
+	// Output:
+	// "POST / HTTP/1.1\r\nHost: www.example.org\r\nAccept-Encoding: gzip\r\nUser-Agent: Go-http-client/1.1\r\n\r\nGo is a general-purpose language designed with systems programming in mind."
+}
+
+func ExampleDumpRequestOut() {
+	const body = "Go is a general-purpose language designed with systems programming in mind."
+	req, err := http.NewRequest("PUT", "http://www.example.org", strings.NewReader(body))
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	dump, err := httputil.DumpRequestOut(req, true)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	fmt.Printf("%q", dump)
+
+	// Output:
+	// "PUT / HTTP/1.1\r\nHost: www.example.org\r\nUser-Agent: Go-http-client/1.1\r\nContent-Length: 75\r\nAccept-Encoding: gzip\r\n\r\nGo is a general-purpose language designed with systems programming in mind."
+}
+
+func ExampleDumpResponse() {
+	const body = "Go is a general-purpose language designed with systems programming in mind."
+	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Date", "Wed, 19 Jul 1972 19:00:00 GMT")
+		fmt.Fprintln(w, body)
+	}))
+	defer ts.Close()
+
+	resp, err := http.Get(ts.URL)
+	if err != nil {
+		log.Fatal(err)
+	}
+	defer resp.Body.Close()
+
+	dump, err := httputil.DumpResponse(resp, true)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	fmt.Printf("%q", dump)
+
+	// Output:
+	// "HTTP/1.1 200 OK\r\nContent-Length: 76\r\nContent-Type: text/plain; charset=utf-8\r\nDate: Wed, 19 Jul 1972 19:00:00 GMT\r\n\r\nGo is a general-purpose language designed with systems programming in mind.\n"
+}
+
+func ExampleReverseProxy() {
+	backendServer := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		fmt.Fprintln(w, "this call was relayed by the reverse proxy")
+	}))
+	defer backendServer.Close()
+
+	rpURL, err := url.Parse(backendServer.URL)
+	if err != nil {
+		log.Fatal(err)
+	}
+	frontendProxy := httptest.NewServer(httputil.NewSingleHostReverseProxy(rpURL))
+	defer frontendProxy.Close()
+
+	resp, err := http.Get(frontendProxy.URL)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	b, err := ioutil.ReadAll(resp.Body)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	fmt.Printf("%s", b)
+
+	// Output:
+	// this call was relayed by the reverse proxy
+}