os: TestRemoveAllWithMoreErrorThanReqSize is failing on Plan 9 and Windows

[fhs]

What version of Go are you using (go version)?

cpu% go version
go version devel +master Wed Oct 23 01:24:58 EDT 2019 plan9/386

What operating system and processor architecture are you using (go env)?

go env Output

$ go env
GO111MODULE='on'
GOARCH='386'
GOBIN=''
GOCACHE='/usr/fhs/lib/cache/go-build'
GOENV='/usr/fhs/lib/go/env'
GOEXE=''
GOFLAGS=''
GOHOSTARCH='386'
GOHOSTOS='plan9'
GONOPROXY=''
GONOSUMDB=''
GOOS='plan9'
GOPATH='/home/fhs/go'
GOPRIVATE=''
GOPROXY='https://proxy.golang.org,direct'
GOROOT='/home/big/go'
GOSUMDB='sum.golang.org'
GOTMPDIR=''
GOTOOLDIR='/home/big/go/pkg/tool/plan9_386'
GCCGO='gccgo'
GO386='sse2'
AR='ar'
CC='8c'
CXX='g++'
CGO_ENABLED='0'
GOMOD='/dev/null'
CGO_CFLAGS='-g -O2'
CGO_CPPFLAGS=''
CGO_CXXFLAGS='-g -O2'
CGO_FFLAGS='-g -O2'
CGO_LDFLAGS='-g -O2'
PKG_CONFIG='pkg-config'
GOGCCFLAGS='-fPIC -m32 -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build107333689=/tmp/go-build -gno-record-gcc-switches'

What did you do?

cpu% cd src/os
cpu% go test

What did you expect to see?

All tests passed.

What did you see instead?

--- FAIL: TestRemoveAllWithMoreErrorThanReqSize (0.30s)
    removeall_test.go:447: Want error from RemoveAllTestHook, got nil
FAIL
exit status: 'os.test 129292: 1'
FAIL	os	2.458s

This test doesn't get run with the -short flag, so it's probably not getting run on the plan9 builders.

On Plan 9, we use the "noat" implementation, which is slightly different from the "at" implementation in that it can Remove the parent directory within the for-loop in addition to the Remove at the end of the function.

This test tries to delete 1025 files. The first Readdirnames returns 1024 entries. In the second Readdirnames call, we get the 1 remaining entry. After deleting that one entry, instead of breaking out of the loop, the code tries to Remove the parent directory. Since the Remove succeeds, we return nil. I believe we need to an add additional hook right after this Remove call, and another hook right after we try to Open the deleted parent directory (only reached if hook is set by the test).

@gopherbot Please add labels OS-Plan9, NeedsFix

[gopherbot]

Change https://golang.org/cl/202757 mentions this issue: os: fix TestRemoveAllWithMoreErrorThanReqSize on Plan 9

[bradfitz]

It's also failing on Windows:
https://storage.googleapis.com/go-build-log/f58f8d03/windows-amd64-longtest_dc0788fb.log

[gopherbot]

Change https://golang.org/cl/203502 mentions this issue: os: use an actual RemoveAll failure in TestRemoveAllWithMoreErrorThanReqSize

[iwdgo]

The test still fails on Windows.
Previous error was:

golang\go\src>go test os -v -run=RemoveAllWithMore
=== RUN   TestRemoveAllWithMoreErrorThanReqSize
--- FAIL: TestRemoveAllWithMoreErrorThanReqSize (1.72s)
    removeall_test.go:447: Want error from RemoveAllTestHook, got nil
FAIL

On tip, error is now:

golang\go\src>goissue test os -v -run=RemoveAllWithMore
=== RUN   TestRemoveAllWithMoreErrorThanReqSize
    TestRemoveAllWithMoreErrorThanReqSize: removeall_test.go:452: RemoveAll(<read-only directory>) = nil; want error
--- FAIL: TestRemoveAllWithMoreErrorThanReqSize (1.08s)

Following #26295 (and others) and as documented, RemoveAll is expected to remove everything it can. The proposed commit removes completely the now unused test hook and returns successfully for Windows.

[gopherbot]

Change https://golang.org/cl/204060 mentions this issue: os: return successfully TestRemoveAllWithMoreErrorThanReqSize on Windows

[gopherbot]

Change https://golang.org/cl/223700 mentions this issue: [release-branch.go1.13] os: use an actual RemoveAll failure in TestRemoveAllWithMoreErrorThanReqSize

[dmitshur]

@gopherbot, please backport to Go 1.13. This is a test fix. It is needed to resolve a test failure in the os package on windows-amd64-longtest builder, which could be masking other problems (due to #36181) and making releasing Go 1.13.x more difficult.

[gopherbot]

Backport issue(s) opened: #37895 (for 1.13).

Remember to create the cherry-pick CL(s) as soon as the patch is submitted to master, according to https://golang.org/wiki/MinorReleases.