net/http: remove arbitrary timeouts in tests of Server.ErrorLog

This also allows us to remove the chanWriter helper from the test,
using a simpler strings.Builder instead, relying on
clientServerTest.close for synchronization.
(I don't think this runs afoul of #38370, because the handler
functions themselves in these tests should never be executed,
let alone result in an asynchronous write to the error log.)

Fixes #57599.

Change-Id: I45c6cefca0bb218f6f9a9659de6bde454547f704
Reviewed-on: https://go-review.googlesource.com/c/go/+/539436
Run-TryBot: Bryan Mills <bcmills@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Auto-Submit: Bryan Mills <bcmills@google.com>
Reviewed-by: Damien Neil <dneil@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>

1 files changed, 9 insertions, 8 deletions

diff --git a/src/net/http/serve_test.go b/src/net/http/serve_test.go
index 00230020e7..0c76f1bcc4 100644
--- a/src/net/http/serve_test.go
+++ b/src/net/http/serve_test.go
@@ -1400,27 +1400,28 @@ func TestTLSHandshakeTimeout(t *testing.T) {
 	run(t, testTLSHandshakeTimeout, []testMode{https1Mode, http2Mode})
 }
 func testTLSHandshakeTimeout(t *testing.T, mode testMode) {
-	errc := make(chanWriter, 10) // but only expecting 1
-	ts := newClientServerTest(t, mode, HandlerFunc(func(w ResponseWriter, r *Request) {}),
+	errLog := new(strings.Builder)
+	cst := newClientServerTest(t, mode, HandlerFunc(func(w ResponseWriter, r *Request) {}),
 		func(ts *httptest.Server) {
 			ts.Config.ReadTimeout = 250 * time.Millisecond
-			ts.Config.ErrorLog = log.New(errc, "", 0)
+			ts.Config.ErrorLog = log.New(errLog, "", 0)
 		},
-	).ts
+	)
+	ts := cst.ts
+
 	conn, err := net.Dial("tcp", ts.Listener.Addr().String())
 	if err != nil {
 		t.Fatalf("Dial: %v", err)
 	}
-	defer conn.Close()
-
 	var buf [1]byte
 	n, err := conn.Read(buf[:])
 	if err == nil || n != 0 {
 		t.Errorf("Read = %d, %v; want an error and no bytes", n, err)
 	}
+	conn.Close()
 
-	v := <-errc
-	if !strings.Contains(v, "timeout") && !strings.Contains(v, "TLS handshake") {
+	cst.close()
+	if v := errLog.String(); !strings.Contains(v, "timeout") && !strings.Contains(v, "TLS handshake") {
 		t.Errorf("expected a TLS handshake timeout error; got %q", v)
 	}
 }