net/http: deflake TestTimeoutHandlerContextCanceled

Fixes #49448

Change-Id: Ie2acff7dedbca9bd1cc0b1b3dd0a01573c7befee
Reviewed-on: https://go-review.googlesource.com/c/go/+/361920
Trust: Damien Neil <dneil@google.com>
Run-TryBot: Damien Neil <dneil@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Bryan C. Mills <bcmills@google.com>

diff --git a/src/net/http/serve_test.go b/src/net/http/serve_test.go
index 27dff2bf458d899e5ef0c1c4bd1c77be7b079113..30a6555d30cdf7ff72b49378aeef45fffc30dc86 100644 (file)
--- a/src/net/http/serve_test.go
+++ b/src/net/http/serve_test.go
@@ -2520,22 +2520,28 @@ func TestTimeoutHandlerStartTimerWhenServing(t *testing.T) {
 func TestTimeoutHandlerContextCanceled(t *testing.T) {
        setParallel(t)
        defer afterTest(t)
-       sendHi := make(chan bool, 1)
        writeErrors := make(chan error, 1)
        sayHi := HandlerFunc(func(w ResponseWriter, r *Request) {
                w.Header().Set("Content-Type", "text/plain")
-               <-sendHi
-               _, werr := w.Write([]byte("hi"))
-               writeErrors <- werr
+               var err error
+               // The request context has already been canceled, but
+               // retry the write for a while to give the timeout handler
+               // a chance to notice.
+               for i := 0; i < 100; i++ {
+                       _, err = w.Write([]byte("a"))
+                       if err != nil {
+                               break
+                       }
+                       time.Sleep(1 * time.Millisecond)
+               }
+               writeErrors <- err
        })
-       ctx, cancel := context.WithTimeout(context.Background(), 1*time.Hour)
-       h := NewTestTimeoutHandler(sayHi, ctx)
+       ctx, cancel := context.WithCancel(context.Background())
        cancel()
+       h := NewTestTimeoutHandler(sayHi, ctx)
        cst := newClientServerTest(t, h1Mode, h)
        defer cst.close()
 
-       // Succeed without timing out:
-       sendHi <- true
        res, err := cst.c.Get(cst.ts.URL)
        if err != nil {
                t.Error(err)
@@ -2548,7 +2554,7 @@ func TestTimeoutHandlerContextCanceled(t *testing.T) {
                t.Errorf("got body %q; expected %q", g, e)
        }
        if g, e := <-writeErrors, context.Canceled; g != e {
-               t.Errorf("got unexpected Write error on first request: %v", g)
+               t.Errorf("got unexpected Write in handler: %v, want %g", g, e)
        }
 }