The program in https://play.golang.org/p/rV-CkJivlXs fails under go test -race:
func TestBackgroundCleanup(t *testing.T) {
helperDone := make(chan struct{})
go func() {
t.Logf("Something happened before cleanup.")
close(helperDone)
}()
t.Cleanup(func() {
<-helperDone
})
}$ go version
go version devel +d3a411b6 Wed Aug 19 03:56:26 2020 +0000 linux/amd64
$ go test -race
==================
WARNING: DATA RACE
Read at 0x00c000001858 by goroutine 8:
testing.(*common).frameSkip()
/usr/local/google/home/bcmills/sdk/gotip/src/testing/testing.go:488 +0x26e
testing.(*common).decorate()
/usr/local/google/home/bcmills/sdk/gotip/src/testing/testing.go:533 +0x64
testing.(*common).logDepth()
/usr/local/google/home/bcmills/sdk/gotip/src/testing/testing.go:760 +0x5ab
testing.(*common).log()
/usr/local/google/home/bcmills/sdk/gotip/src/testing/testing.go:729 +0x8f
testing.(*common).Logf()
/usr/local/google/home/bcmills/sdk/gotip/src/testing/testing.go:775 +0x21
example%2ecom.TestBackgroundCleanup.func1()
/tmp/tmp.BqaVZz8DDs/example.com/main_test.go:8 +0x64
Previous write at 0x00c000001858 by goroutine 7:
testing.(*common).Cleanup.func1()
/usr/local/google/home/bcmills/sdk/gotip/src/testing/testing.go:867 +0xba
testing.(*common).runCleanup()
/usr/local/google/home/bcmills/sdk/gotip/src/testing/testing.go:945 +0xca
testing.tRunner.func2()
/usr/local/google/home/bcmills/sdk/gotip/src/testing/testing.go:1117 +0x74
testing.tRunner()
/usr/local/google/home/bcmills/sdk/gotip/src/testing/testing.go:1127 +0x22a
Goroutine 8 (running) created at:
example%2ecom.TestBackgroundCleanup()
/tmp/tmp.BqaVZz8DDs/example.com/main_test.go:7 +0x78
testing.tRunner()
/usr/local/google/home/bcmills/sdk/gotip/src/testing/testing.go:1123 +0x202
Goroutine 7 (running) created at:
testing.(*T).Run()
/usr/local/google/home/bcmills/sdk/gotip/src/testing/testing.go:1174 +0x796
testing.runTests.func1()
/usr/local/google/home/bcmills/sdk/gotip/src/testing/testing.go:1445 +0xa6
testing.tRunner()
/usr/local/google/home/bcmills/sdk/gotip/src/testing/testing.go:1123 +0x202
testing.runTests()
/usr/local/google/home/bcmills/sdk/gotip/src/testing/testing.go:1443 +0x5aa
testing.(*M).Run()
/usr/local/google/home/bcmills/sdk/gotip/src/testing/testing.go:1353 +0x4eb
main.main()
_testmain.go:43 +0x236
==================
--- FAIL: TestBackgroundCleanup (0.00s)
main_test.go:8: Something happened before cleanup.
testing.go:1038: race detected during execution of test
FAIL
exit status 1
FAIL example.com 0.019s
I think this race should be fixed, because this usage seems reasonable to me: for example, calling t.Logf directly from the Cleanup callback does not race, and it seems very odd to allow t.Logf before and after cleanup begins but not during.
CC @rogpeppe @ianlancetaylor @bradfitz
The program in https://play.golang.org/p/rV-CkJivlXs fails under
go test -race:I think this race should be fixed, because this usage seems reasonable to me: for example, calling
t.Logfdirectly from theCleanupcallback does not race, and it seems very odd to allowt.Logfbefore and after cleanup begins but not during.CC @rogpeppe @ianlancetaylor @bradfitz