net: fix flaky *TimeoutMustNotReturn tests

The tester goroutine doesn't always gets a chance to run before the
timeout expires. Wait for the goroutine to start and set deadlines
before staring the timer.

Fixes #36796

Change-Id: Iffed6259de31340c3f66e34da473826a1d09fcde
Reviewed-on: https://go-review.googlesource.com/c/go/+/412858
Reviewed-by: Damien Neil <dneil@google.com>
Run-TryBot: Bryan Mills <bcmills@google.com>
Reviewed-by: Bryan Mills <bcmills@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>

diff --git a/src/net/timeout_test.go b/src/net/timeout_test.go
index d1cfbf853cbb4a77b7860b0897e58366ee5ffa07..3ad026c49088bb836b09cbc67f1c6378699eaa32 100644 (file)
--- a/src/net/timeout_test.go
+++ b/src/net/timeout_test.go
@@ -243,8 +243,7 @@ func TestAcceptTimeoutMustNotReturn(t *testing.T) {
        ln := newLocalListener(t, "tcp")
        defer ln.Close()
 
-       max := time.NewTimer(100 * time.Millisecond)
-       defer max.Stop()
+       maxch := make(chan *time.Timer)
        ch := make(chan error)
        go func() {
                if err := ln.(*TCPListener).SetDeadline(time.Now().Add(-5 * time.Second)); err != nil {
@@ -253,10 +252,14 @@ func TestAcceptTimeoutMustNotReturn(t *testing.T) {
                if err := ln.(*TCPListener).SetDeadline(noDeadline); err != nil {
                        t.Error(err)
                }
+               maxch <- time.NewTimer(100 * time.Millisecond)
                _, err := ln.Accept()
                ch <- err
        }()
 
+       max := <-maxch
+       defer max.Stop()
+
        select {
        case err := <-ch:
                if perr := parseAcceptError(err); perr != nil {
@@ -348,8 +351,7 @@ func TestReadTimeoutMustNotReturn(t *testing.T) {
        }
        defer c.Close()
 
-       max := time.NewTimer(100 * time.Millisecond)
-       defer max.Stop()
+       maxch := make(chan *time.Timer)
        ch := make(chan error)
        go func() {
                if err := c.SetDeadline(time.Now().Add(-5 * time.Second)); err != nil {
@@ -361,11 +363,15 @@ func TestReadTimeoutMustNotReturn(t *testing.T) {
                if err := c.SetReadDeadline(noDeadline); err != nil {
                        t.Error(err)
                }
+               maxch <- time.NewTimer(100 * time.Millisecond)
                var b [1]byte
                _, err := c.Read(b[:])
                ch <- err
        }()
 
+       max := <-maxch
+       defer max.Stop()
+
        select {
        case err := <-ch:
                if perr := parseReadError(err); perr != nil {
@@ -517,8 +523,7 @@ func TestWriteTimeoutMustNotReturn(t *testing.T) {
        }
        defer c.Close()
 
-       max := time.NewTimer(100 * time.Millisecond)
-       defer max.Stop()
+       maxch := make(chan *time.Timer)
        ch := make(chan error)
        go func() {
                if err := c.SetDeadline(time.Now().Add(-5 * time.Second)); err != nil {
@@ -530,6 +535,7 @@ func TestWriteTimeoutMustNotReturn(t *testing.T) {
                if err := c.SetWriteDeadline(noDeadline); err != nil {
                        t.Error(err)
                }
+               maxch <- time.NewTimer(100 * time.Millisecond)
                var b [1]byte
                for {
                        if _, err := c.Write(b[:]); err != nil {
@@ -539,6 +545,9 @@ func TestWriteTimeoutMustNotReturn(t *testing.T) {
                }
        }()
 
+       max := <-maxch
+       defer max.Stop()
+
        select {
        case err := <-ch:
                if perr := parseWriteError(err); perr != nil {