From f4f8397fed02b612c36c425fc9c5dce32408e21b Mon Sep 17 00:00:00 2001
From: Damien Neil <dneil@google.com>
Date: Fri, 18 Nov 2022 14:10:50 -0800
Subject: [PATCH] net/http: deflake TestIssue4191_InfiniteGetTimeout

This test exercises the case where a net.Conn error occurs while
writing a response body. It injects an error by setting a timeout
on the Conn. If this timeout expires before response headers are
written, the test fails. The test attempts to recover from this
failure by extending the timeout and retrying.

Set the timeout after the response headers are removed, and
remove the retry loop.

Fixes #56274.

Change-Id: I293f8bedb7b20a21d14f43ea9bb48fc56b59441c
Reviewed-on: https://go-review.googlesource.com/c/go/+/452175
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Bryan Mills <bcmills@google.com>
Run-TryBot: Damien Neil <dneil@google.com>
---
 src/net/http/transport_test.go | 48 ++++++++++------------------------
 1 file changed, 14 insertions(+), 34 deletions(-)

diff --git a/src/net/http/transport_test.go b/src/net/http/transport_test.go
index c0cabccab82..2bc83fd42b2 100644
--- a/src/net/http/transport_test.go
+++ b/src/net/http/transport_test.go
@@ -2224,57 +2224,37 @@ func testTransportConcurrency(t *testing.T, mode testMode) {
 
 func TestIssue4191_InfiniteGetTimeout(t *testing.T) { run(t, testIssue4191_InfiniteGetTimeout) }
 func testIssue4191_InfiniteGetTimeout(t *testing.T, mode testMode) {
-	const debug = false
 	mux := NewServeMux()
 	mux.HandleFunc("/get", func(w ResponseWriter, r *Request) {
 		io.Copy(w, neverEnding('a'))
 	})
 	ts := newClientServerTest(t, mode, mux).ts
-	timeout := 100 * time.Millisecond
 
+	connc := make(chan net.Conn, 1)
 	c := ts.Client()
 	c.Transport.(*Transport).Dial = func(n, addr string) (net.Conn, error) {
 		conn, err := net.Dial(n, addr)
 		if err != nil {
 			return nil, err
 		}
-		conn.SetDeadline(time.Now().Add(timeout))
-		if debug {
-			conn = NewLoggingConn("client", conn)
+		select {
+		case connc <- conn:
+		default:
 		}
 		return conn, nil
 	}
 
-	getFailed := false
-	nRuns := 5
-	if testing.Short() {
-		nRuns = 1
+	res, err := c.Get(ts.URL + "/get")
+	if err != nil {
+		t.Fatalf("Error issuing GET: %v", err)
 	}
-	for i := 0; i < nRuns; i++ {
-		if debug {
-			println("run", i+1, "of", nRuns)
-		}
-		sres, err := c.Get(ts.URL + "/get")
-		if err != nil {
-			if !getFailed {
-				// Make the timeout longer, once.
-				getFailed = true
-				t.Logf("increasing timeout")
-				i--
-				timeout *= 10
-				continue
-			}
-			t.Errorf("Error issuing GET: %v", err)
-			break
-		}
-		_, err = io.Copy(io.Discard, sres.Body)
-		if err == nil {
-			t.Errorf("Unexpected successful copy")
-			break
-		}
-	}
-	if debug {
-		println("tests complete; waiting for handlers to finish")
+	defer res.Body.Close()
+
+	conn := <-connc
+	conn.SetDeadline(time.Now().Add(1 * time.Millisecond))
+	_, err = io.Copy(io.Discard, res.Body)
+	if err == nil {
+		t.Errorf("Unexpected successful copy")
 	}
 }