net/http: documentation updates

Fixes #10366 (how to set custom headers)
Fixes #9836 (PATCH in PostForm)
Fixes #9276 (generating a server-side Request for testing)
Update #8991 (clarify Response.Write for now; export ReverseProxy's copy later?)

Change-Id: I95a11bf3bb3eeeeb72775b6ebfbc761641addc35
Reviewed-on: https://go-review.googlesource.com/9410
Reviewed-by: David Crawshaw <crawshaw@golang.org>

src/net/http/client.go

@@ -257,8 +257,9 @@ func shouldRedirectPost(statusCode int) bool {
 	return false
 }
 
-// Get issues a GET to the specified URL.  If the response is one of the following
-// redirect codes, Get follows the redirect, up to a maximum of 10 redirects:
+// Get issues a GET to the specified URL. If the response is one of
+// the following redirect codes, Get follows the redirect, up to a
+// maximum of 10 redirects:
 //
 //    301 (Moved Permanently)
 //    302 (Found)
@@ -273,11 +274,14 @@ func shouldRedirectPost(statusCode int) bool {
 // Caller should close resp.Body when done reading from it.
 //
 // Get is a wrapper around DefaultClient.Get.
+//
+// To make a request with custom headers, use NewRequest and
+// DefaultClient.Do.
 func Get(url string) (resp *Response, err error) {
 	return DefaultClient.Get(url)
 }
 
-// Get issues a GET to the specified URL.  If the response is one of the
+// Get issues a GET to the specified URL. If the response is one of the
 // following redirect codes, Get follows the redirect after calling the
 // Client's CheckRedirect function.
 //
@@ -292,6 +296,8 @@ func Get(url string) (resp *Response, err error) {
 //
 // When err is nil, resp always contains a non-nil resp.Body.
 // Caller should close resp.Body when done reading from it.
+//
+// To make a request with custom headers, use NewRequest and Client.Do.
 func (c *Client) Get(url string) (resp *Response, err error) {
 	req, err := NewRequest("GET", url, nil)
 	if err != nil {
@@ -438,7 +444,12 @@ func defaultCheckRedirect(req *Request, via []*Request) error {
 //
 // Caller should close resp.Body when done reading from it.
 //
-// Post is a wrapper around DefaultClient.Post
+// If the provided body is an io.Closer, it is closed after the
+// request.
+//
+// Post is a wrapper around DefaultClient.Post.
+//
+// To set custom headers, use NewRequest and DefaultClient.Do.
 func Post(url string, bodyType string, body io.Reader) (resp *Response, err error) {
 	return DefaultClient.Post(url, bodyType, body)
 }
@@ -447,8 +458,10 @@ func Post(url string, bodyType string, body io.Reader) (resp *Response, err erro
 //
 // Caller should close resp.Body when done reading from it.
 //
-// If the provided body is also an io.Closer, it is closed after the
+// If the provided body is an io.Closer, it is closed after the
 // request.
+//
+// To set custom headers, use NewRequest and Client.Do.
 func (c *Client) Post(url string, bodyType string, body io.Reader) (resp *Response, err error) {
 	req, err := NewRequest("POST", url, body)
 	if err != nil {
@@ -461,16 +474,22 @@ func (c *Client) Post(url string, bodyType string, body io.Reader) (resp *Respon
 // PostForm issues a POST to the specified URL, with data's keys and
 // values URL-encoded as the request body.
 //
+// The Content-Type header is set to application/x-www-form-urlencoded.
+// To set other headers, use NewRequest and DefaultClient.Do.
+//
 // When err is nil, resp always contains a non-nil resp.Body.
 // Caller should close resp.Body when done reading from it.
 //
-// PostForm is a wrapper around DefaultClient.PostForm
+// PostForm is a wrapper around DefaultClient.PostForm.
 func PostForm(url string, data url.Values) (resp *Response, err error) {
 	return DefaultClient.PostForm(url, data)
 }
 
 // PostForm issues a POST to the specified URL,
-// with data's keys and values urlencoded as the request body.
+// with data's keys and values URL-encoded as the request body.
+//
+// The Content-Type header is set to application/x-www-form-urlencoded.
+// To set other headers, use NewRequest and DefaultClient.Do.
 //
 // When err is nil, resp always contains a non-nil resp.Body.
 // Caller should close resp.Body when done reading from it.

src/net/http/request.go

@@ -169,8 +169,9 @@ type Request struct {
 	// The HTTP client ignores Form and uses Body instead.
 	Form url.Values
 
-	// PostForm contains the parsed form data from POST or PUT
-	// body parameters.
+	// PostForm contains the parsed form data from POST, PATCH,
+	// or PUT body parameters.
+	//
 	// This field is only available after ParseForm is called.
 	// The HTTP client ignores PostForm and uses Body instead.
 	PostForm url.Values
@@ -506,6 +507,13 @@ func ParseHTTPVersion(vers string) (major, minor int, ok bool) {
 // If the provided body is also an io.Closer, the returned
 // Request.Body is set to body and will be closed by the Client
 // methods Do, Post, and PostForm, and Transport.RoundTrip.
+//
+// NewRequest returns a Request suitable for use with Client.Do or
+// Transport.RoundTrip.
+// To create a request for use with testing a Server Handler use either
+// ReadRequest or manually update the Request fields. See the Request
+// type's documentation for the difference between inbound and outbound
+// request fields.
 func NewRequest(method, urlStr string, body io.Reader) (*Request, error) {
 	u, err := url.Parse(urlStr)
 	if err != nil {
@@ -605,7 +613,7 @@ func putTextprotoReader(r *textproto.Reader) {
 	textprotoReaderPool.Put(r)
 }
 
-// ReadRequest reads and parses a request from b.
+// ReadRequest reads and parses an incoming request from b.
 func ReadRequest(b *bufio.Reader) (req *Request, err error) {
 
 	tp := newTextprotoReader(b)

src/net/http/response.go

@@ -189,8 +189,10 @@ func (r *Response) ProtoAtLeast(major, minor int) bool {
 		r.ProtoMajor == major && r.ProtoMinor >= minor
 }
 
-// Writes the response (header, body and trailer) in wire format. This method
-// consults the following fields of the response:
+// Write writes r to w in the HTTP/1.n server response format,
+// including the status line, headers, body, and optional trailer.
+//
+// This method consults the following fields of the response r:
 //
 //  StatusCode
 //  ProtoMajor
@@ -202,7 +204,7 @@ func (r *Response) ProtoAtLeast(major, minor int) bool {
 //  ContentLength
 //  Header, values for non-canonical keys will have unpredictable behavior
 //
-// Body is closed after it is sent.
+// The Response Body is closed after it is sent.
 func (r *Response) Write(w io.Writer) error {
 	// Status line
 	text := r.Status