integration: Use []hpack.HeaderField instead of http.Header in requestParam

With array, we can control the order of header field directly.

integration-tests/nghttpx_test.go

@@ -3,6 +3,7 @@ package nghttp2
 import (
 	"fmt"
 	"github.com/bradfitz/http2"
+	"github.com/bradfitz/http2/hpack"
 	"net/http"
 	"testing"
 )
@@ -54,8 +55,8 @@ func TestAddXff2(t *testing.T) {
 
 	_, err := st.http2(requestParam{
 		name: "TestAddXff2",
-		header: http.Header{
-			"x-forwarded-for": []string{"host"},
+		header: []hpack.HeaderField{
+			pair("x-forwarded-for", "host"),
 		},
 	})
 	if err != nil {
@@ -73,8 +74,8 @@ func TestStripXff(t *testing.T) {
 
 	_, err := st.http2(requestParam{
 		name: "TestStripXff1",
-		header: http.Header{
-			"x-forwarded-for": []string{"host"},
+		header: []hpack.HeaderField{
+			pair("x-forwarded-for", "host"),
 		},
 	})
 	if err != nil {
@@ -98,8 +99,8 @@ func TestStripAddXff(t *testing.T) {
 
 	_, err := st.http2(requestParam{
 		name: "TestStripAddXff",
-		header: http.Header{
-			"x-forwarded-for": []string{"host"},
+		header: []hpack.HeaderField{
+			pair("x-forwarded-for", "host"),
 		},
 	})
 	if err != nil {
@@ -116,8 +117,8 @@ func TestHTTP2BadRequestCL(t *testing.T) {
 	res, err := st.http2(requestParam{
 		name:   "TestHTTP2BadRequestCL",
 		method: "POST",
-		header: http.Header{
-			"content-length": []string{"1024"},
+		header: []hpack.HeaderField{
+			pair("content-length", "1024"),
 		},
 		body: []byte("foo"),
 	})

integration-tests/server_tester.go

@@ -134,14 +134,13 @@ func (st *serverTester) readFrame() (http2.Frame, error) {
 }
 
 type requestParam struct {
-	name string // name for this request to identify the request
-	// in log easily
+	name      string              // name for this request to identify the request in log easily
 	streamID  uint32              // stream ID, automatically assigned if 0
 	method    string              // method, defaults to GET
 	scheme    string              // scheme, defaults to http
 	authority string              // authority, defaults to backend server address
 	path      string              // path, defaults to /
-	header    http.Header // additional request header fields
+	header    []hpack.HeaderField // additional request header fields
 	body      []byte              // request body
 }
 
@@ -195,10 +194,8 @@ func (st *serverTester) http2(rp requestParam) (*serverResponse, error) {
 
 	_ = st.enc.WriteField(pair("test-case", rp.name))
 
-	for k, v := range rp.header {
-		for _, h := range v {
-			_ = st.enc.WriteField(pair(strings.ToLower(k), h))
-		}
+	for _, h := range rp.header {
+		_ = st.enc.WriteField(pair(strings.ToLower(h.Name), h.Value))
 	}
 
 	err := st.fr.WriteHeaders(http2.HeadersFrameParam{