From b68cebd809f1335b4504837337f5702406720432 Mon Sep 17 00:00:00 2001 From: Damien Neil Date: Tue, 14 Oct 2025 11:25:29 -0700 Subject: [PATCH] net/http/httptest: record failed ResponseWriter writes CL 709335 changed ResponseWriter.Write to return an error when trying to write to a response with a status code which doesn't permit a body, such as 304. Continue to return an error, but still record the write in ResponseWriter.Body. This maintains the documented property that "the data in buf is written to rw.Body". For #75471 Change-Id: I69139797559fe09d6580c5d25b4458f04263c60e Reviewed-on: https://go-review.googlesource.com/c/go/+/711940 Reviewed-by: Sean Liao TryBot-Bypass: Damien Neil Auto-Submit: Damien Neil Reviewed-by: Nicholas Husin Reviewed-by: Nicholas Husin --- src/net/http/httptest/recorder.go | 16 ++++++++-------- src/net/http/httptest/recorder_test.go | 10 ++++++++-- 2 files changed, 16 insertions(+), 10 deletions(-) diff --git a/src/net/http/httptest/recorder.go b/src/net/http/httptest/recorder.go index 7890b5ef6b..4006f4406d 100644 --- a/src/net/http/httptest/recorder.go +++ b/src/net/http/httptest/recorder.go @@ -105,28 +105,28 @@ func (rw *ResponseRecorder) writeHeader(b []byte, str string) { // Write implements http.ResponseWriter. The data in buf is written to // rw.Body, if not nil. func (rw *ResponseRecorder) Write(buf []byte) (int, error) { - code := rw.Code - if !bodyAllowedForStatus(code) { - return 0, http.ErrBodyNotAllowed - } + // Record the write, even if we're going to return an error. rw.writeHeader(buf, "") if rw.Body != nil { rw.Body.Write(buf) } + if !bodyAllowedForStatus(rw.Code) { + return 0, http.ErrBodyNotAllowed + } return len(buf), nil } // WriteString implements [io.StringWriter]. The data in str is written // to rw.Body, if not nil. func (rw *ResponseRecorder) WriteString(str string) (int, error) { - code := rw.Code - if !bodyAllowedForStatus(code) { - return 0, http.ErrBodyNotAllowed - } + // Record the write, even if we're going to return an error. rw.writeHeader(nil, str) if rw.Body != nil { rw.Body.WriteString(str) } + if !bodyAllowedForStatus(rw.Code) { + return 0, http.ErrBodyNotAllowed + } return len(str), nil } diff --git a/src/net/http/httptest/recorder_test.go b/src/net/http/httptest/recorder_test.go index abf8e118d6..0996976514 100644 --- a/src/net/http/httptest/recorder_test.go +++ b/src/net/http/httptest/recorder_test.go @@ -5,6 +5,7 @@ package httptest import ( + "bytes" "errors" "fmt" "io" @@ -312,17 +313,22 @@ func TestRecorder(t *testing.T) { func TestBodyNotAllowed(t *testing.T) { rw := NewRecorder() + rw.Body = new(bytes.Buffer) rw.WriteHeader(204) - _, err := rw.Write([]byte("hello world")) + _, err := rw.Write([]byte("hello ")) if !errors.Is(err, http.ErrBodyNotAllowed) { t.Errorf("expected BodyNotAllowed for Write after 204, got: %v", err) } - _, err = rw.WriteString("hello world") + _, err = rw.WriteString("world") if !errors.Is(err, http.ErrBodyNotAllowed) { t.Errorf("expected BodyNotAllowed for WriteString after 204, got: %v", err) } + + if got, want := rw.Body.String(), "hello world"; got != want { + t.Errorf("got Body=%q, want %q", got, want) + } } // issue 39017 - disallow Content-Length values such as "+3" -- 2.52.0