new API

src/net/http/httptest/recorder.go

@@ -9,14 +9,24 @@ import (
 	"fmt"
 	"io"
 	"net/http"
-	"net/http/httptrace"
 	"net/textproto"
 	"strconv"
 	"strings"
 
 	"golang.org/x/net/http/httpguts"
 )
 
+// InformationalResponse is an HTTP response sent with a [1xx status code].
+//
+// [1xx status code]: https://httpwg.org/specs/rfc9110.html#status.1xx
+type InformationalResponse struct {
+	// Code is the 1xx HTTP response code of this informational response.
+	Code int
+
+	// Header contains the headers of this informational response.
+	Header http.Header
+}
+
 // ResponseRecorder is an implementation of http.ResponseWriter that
 // records its mutations for later inspection in tests.
 type ResponseRecorder struct {
@@ -28,6 +38,9 @@ type ResponseRecorder struct {
 	// method.
 	Code int
 
+	// Informational HTTP responses (1xx status code) send before the main response.
+	InformationalResponses []InformationalResponse
+
 	// HeaderMap contains the headers explicitly set by the Handler.
 	// It is an internal detail.
 	//
@@ -43,9 +56,6 @@ type ResponseRecorder struct {
 	// Flushed is whether the Handler called Flush.
 	Flushed bool
 
-	// ClientTrace is used to trace 1XX responses
-	ClientTrace *httptrace.ClientTrace
-
 	result      *http.Response // cache of Result's return value
 	snapHeader  http.Header    // snapshot of HeaderMap at first Write
 	wroteHeader bool
@@ -151,24 +161,19 @@ func (rw *ResponseRecorder) WriteHeader(code int) {
 
 	checkWriteHeaderCode(code)
 
-	if rw.ClientTrace != nil && code >= 100 && code < 200 {
-		if code == 100 {
-			rw.ClientTrace.Got100Continue()
-		}
-		// treat 101 as a terminal status, see issue 26161
-		if code != http.StatusSwitchingProtocols {
-			if err := rw.ClientTrace.Got1xxResponse(code, textproto.MIMEHeader(rw.HeaderMap)); err != nil {
-				panic(err)
-			}
-			return
-		}
+	if rw.HeaderMap == nil {
+		rw.HeaderMap = make(http.Header)
+	}
+
+	if code >= 100 && code < 200 {
+		ir := InformationalResponse{code, rw.HeaderMap.Clone()}
+		rw.InformationalResponses = append(rw.InformationalResponses, ir)
+
+		return
 	}
 
 	rw.Code = code
 	rw.wroteHeader = true
-	if rw.HeaderMap == nil {
-		rw.HeaderMap = make(http.Header)
-	}
 	rw.snapHeader = rw.HeaderMap.Clone()
 }
 

src/net/http/httptest/recorder_test.go

@@ -8,8 +8,7 @@ import (
 	"fmt"
 	"io"
 	"net/http"
-	"net/http/httptrace"
-	"net/textproto"
+	"reflect"
 	"testing"
 )
 
@@ -125,6 +124,15 @@ func TestRecorder(t *testing.T) {
 			return nil
 		}
 	}
+	hasInformationalResponses := func(ir []InformationalResponse) checkFunc {
+		return func(rec *ResponseRecorder) error {
+			if !reflect.DeepEqual(ir, rec.InformationalResponses) {
+				return fmt.Errorf("InformationalResponses = %v; want %v", rec.InformationalResponses, ir)
+			}
+
+			return nil
+		}
+	}
 
 	for _, tt := range [...]struct {
 		name   string
@@ -296,6 +304,26 @@ func TestRecorder(t *testing.T) {
 			check(hasResultContents("")), // check we don't crash reading the body
 
 		},
+		{
+			"1xx status code",
+			func(rw http.ResponseWriter, _ *http.Request) {
+				rw.WriteHeader(http.StatusContinue)
+				rw.Header().Add("Foo", "bar")
+
+				rw.WriteHeader(http.StatusEarlyHints)
+				rw.Header().Add("Baz", "bat")
+
+				rw.Header().Del("Foo")
+			},
+			check(
+				hasInformationalResponses([]InformationalResponse{
+					InformationalResponse{100, http.Header{}},
+					InformationalResponse{103, http.Header{"Foo": []string{"bar"}}},
+				}),
+				hasHeader("Baz", "bat"),
+				hasNotHeaders("Foo"),
+			),
+		},
 	} {
 		t.Run(tt.name, func(t *testing.T) {
 			r, _ := http.NewRequest("GET", "http://foo.com/", nil)
@@ -371,58 +399,3 @@ func TestRecorderPanicsOnNonXXXStatusCode(t *testing.T) {
 		})
 	}
 }
-
-func TestRecorderClientTrace(t *testing.T) {
-	handler := func(rw http.ResponseWriter, _ *http.Request) {
-		rw.WriteHeader(http.StatusContinue)
-
-		rw.Header().Add("Foo", "bar")
-		rw.WriteHeader(http.StatusEarlyHints)
-
-		rw.Header().Add("Baz", "bat")
-	}
-
-	var received100, received103 bool
-	trace := &httptrace.ClientTrace{
-		Got100Continue: func() {
-			received100 = true
-		},
-		Got1xxResponse: func(code int, header textproto.MIMEHeader) error {
-			switch code {
-			case http.StatusContinue:
-			case http.StatusEarlyHints:
-				received103 = true
-				if header.Get("Foo") != "bar" {
-					t.Errorf(`Expected Foo=bar, got %s`, header.Get("Foo"))
-				}
-				if header.Get("Bar") != "" {
-					t.Error("Unexpected Bar header")
-				}
-			default:
-				t.Errorf("Unexpected status code %d", code)
-			}
-
-			return nil
-		},
-	}
-
-	r, _ := http.NewRequest("GET", "http://example.org/", nil)
-	rw := NewRecorder()
-	rw.ClientTrace = trace
-	handler(rw, r)
-
-	if !received100 {
-		t.Error("Got100Continue not called")
-	}
-	if !received103 {
-		t.Error("103 request not received")
-	}
-
-	header := rw.Result().Header
-	if header.Get("Foo") != "bar" {
-		t.Errorf("Expected Foo=bar, got %s", header.Get("Foo"))
-	}
-	if header.Get("Baz") != "bat" {
-		t.Errorf("Expected Baz=bat, got %s", header.Get("Baz"))
-	}
-}