net/http/httptest: add NewRequestWithContext

This matches the net/http API.

Updates #59473.

Change-Id: I99917cef3ed42a0b4a2b39230b492be00da8bbfd
Reviewed-on: https://go-review.googlesource.com/c/go/+/548355
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Damien Neil <dneil@google.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>

api/next/59473.txt

@@ -0,0 +1 @@
+pkg net/http/httptest, func NewRequestWithContext(context.Context, string, string, io.Reader) *http.Request #59473

doc/next/6-stdlib/99-minor/net/http/httptest/59473.md

@@ -0,0 +1,2 @@
+The new NewRequestWithContext method creates an incoming request with
+a Context.

src/net/http/httptest/httptest.go

@@ -8,13 +8,19 @@ package httptest
 import (
 	"bufio"
 	"bytes"
+	"context"
 	"crypto/tls"
 	"io"
 	"net/http"
 	"strings"
 )
 
-// NewRequest returns a new incoming server Request, suitable
+// NewRequest wraps NewRequestWithContext using context.Background.
+func NewRequest(method, target string, body io.Reader) *http.Request {
+	return NewRequestWithContext(context.Background(), method, target, body)
+}
+
+// NewRequestWithContext returns a new incoming server Request, suitable
 // for passing to an [http.Handler] for testing.
 //
 // The target is the RFC 7230 "request-target": it may be either a
@@ -37,14 +43,15 @@ import (
 //
 // To generate a client HTTP request instead of a server request, see
 // the NewRequest function in the net/http package.
-func NewRequest(method, target string, body io.Reader) *http.Request {
+func NewRequestWithContext(ctx context.Context, method, target string, body io.Reader) *http.Request {
 	if method == "" {
 		method = "GET"
 	}
 	req, err := http.ReadRequest(bufio.NewReader(strings.NewReader(method + " " + target + " HTTP/1.0\r\n\r\n")))
 	if err != nil {
 		panic("invalid NewRequest arguments; " + err.Error())
 	}
+	req = req.WithContext(ctx)
 
 	// HTTP/1.0 was used above to avoid needing a Host field. Change it to 1.1 here.
 	req.Proto = "HTTP/1.1"

src/net/http/httptest/httptest_test.go

@@ -5,6 +5,7 @@
 package httptest
 
 import (
+	"context"
 	"crypto/tls"
 	"io"
 	"net/http"
@@ -15,6 +16,26 @@ import (
 )
 
 func TestNewRequest(t *testing.T) {
+	got := NewRequest("GET", "/", nil)
+	want := &http.Request{
+		Method:     "GET",
+		Host:       "example.com",
+		URL:        &url.URL{Path: "/"},
+		Header:     http.Header{},
+		Proto:      "HTTP/1.1",
+		ProtoMajor: 1,
+		ProtoMinor: 1,
+		RemoteAddr: "192.0.2.1:1234",
+		RequestURI: "/",
+	}
+	got.Body = nil // before DeepEqual
+	want = want.WithContext(context.Background())
+	if !reflect.DeepEqual(got, want) {
+		t.Errorf("Request mismatch:\n got: %#v\nwant: %#v", got, want)
+	}
+}
+
+func TestNewRequestWithContext(t *testing.T) {
 	for _, tt := range [...]struct {
 		name string
 
@@ -153,14 +174,15 @@ func TestNewRequest(t *testing.T) {
 		},
 	} {
 		t.Run(tt.name, func(t *testing.T) {
-			got := NewRequest(tt.method, tt.uri, tt.body)
+			got := NewRequestWithContext(context.Background(), tt.method, tt.uri, tt.body)
 			slurp, err := io.ReadAll(got.Body)
 			if err != nil {
 				t.Errorf("ReadAll: %v", err)
 			}
 			if string(slurp) != tt.wantBody {
 				t.Errorf("Body = %q; want %q", slurp, tt.wantBody)
 			}
+			tt.want = tt.want.WithContext(context.Background())
 			got.Body = nil // before DeepEqual
 			if !reflect.DeepEqual(got.URL, tt.want.URL) {
 				t.Errorf("Request.URL mismatch:\n got: %#v\nwant: %#v", got.URL, tt.want.URL)