util/expvarx: deflake TestSafeFuncHappyPath with synctest

I probably could've deflaked this without synctest, but might as well use
it now that Go 1.25 has it.

Fixes #15348

Change-Id: I81c9253fcb7eada079f3e943ab5f1e29ba8e8e31
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
This commit is contained in:
Brad Fitzpatrick 2025-09-08 08:46:53 -07:00 committed by Brad Fitzpatrick
parent 14adf5b717
commit 1cb855fb36

View File

@ -9,9 +9,8 @@ import (
"sync"
"sync/atomic"
"testing"
"testing/synctest"
"time"
"tailscale.com/cmd/testwrapper/flakytest"
)
func ExampleNewSafeFunc() {
@ -54,19 +53,21 @@ func ExampleNewSafeFunc() {
}
func TestSafeFuncHappyPath(t *testing.T) {
flakytest.Mark(t, "https://github.com/tailscale/tailscale/issues/15348")
synctest.Test(t, func(t *testing.T) {
var count int
f := NewSafeFunc(expvar.Func(func() any {
count++
return count
}), time.Millisecond, nil)
}), time.Second, nil)
if got, want := f.Value(), 1; got != want {
t.Errorf("got %v, want %v", got, want)
}
time.Sleep(5 * time.Second) // (fake time in synctest)
if got, want := f.Value(), 2; got != want {
t.Errorf("got %v, want %v", got, want)
}
})
}
func TestSafeFuncSlow(t *testing.T) {