testing: TempDir fails when TMPDIR is a relative directory and os.Chdir() is called

[arp242]

Go version

1.22.4

Output of go env in your module/workspace:

GO111MODULE=''
GOARCH='amd64'
GOBIN='/home/martin/.local/gobin'
GOCACHE='/home/martin/.cache/go/cache'
GOENV='/home/martin/.config/go/env'
GOEXE=''
GOEXPERIMENT=''
GOFLAGS='-modcacherw'
GOHOSTARCH='amd64'
GOHOSTOS='linux'
GOINSECURE=''
GOMODCACHE='/home/martin/.cache/go/pkg/mod'
GONOPROXY=''
GONOSUMDB=''
GOOS='linux'
GOPATH='/home/martin/.cache/go'
GOPRIVATE=''
GOPROXY='https://proxy.golang.org,direct'
GOROOT='/usr/lib/go'
GOSUMDB='sum.golang.org'
GOTMPDIR='/home/martin/.cache/go/tmp'
GOTOOLCHAIN='auto'
GOTOOLDIR='/usr/lib/go/pkg/tool/linux_amd64'
GOVCS=''
GOVERSION='go1.22.4'
GCCGO='gccgo'
GOAMD64='v1'
AR='ar'
CC='cc'
CXX='c++'
CGO_ENABLED='1'
GOMOD='/home/martin/testtmp/go.mod'
GOWORK=''
CGO_CFLAGS='-O2 -g'
CGO_CPPFLAGS=''
CGO_CXXFLAGS='-O2 -g'
CGO_FFLAGS='-O2 -g'
CGO_LDFLAGS='-O2 -g'
PKG_CONFIG='pkg-config'
GOGCCFLAGS='-fPIC -m64 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -ffile-prefix-map=/home/martin/.cache/go/tmp/go-build3133883126=/tmp/go-build -gno-record-gcc-switches'

---

Setup:

% mkdir tmp
% go mod init testtemp

% cat test_test.go
package main

import (
	"fmt"
	"os"
	"testing"
)

func TestTest(t *testing.T) {
	fmt.Println(t.TempDir())
	fmt.Println(t.TempDir())
	os.Chdir("./tmp")
	fmt.Println(t.TempDir())
}

This runs fine:

% go test
/tmp/TestTest731866446/001
/tmp/TestTest731866446/002
/tmp/TestTest731866446/003

But when setting TMPDIR to ./tmp it stops working after the os.Chdir() call:

% TMPDIR=./tmp go test
./tmp/TestTest4094023708/001
./tmp/TestTest4094023708/002
--- FAIL: TestTest (0.00s)
	test_test.go:13: TempDir: stat ./tmp: no such file or directory
FAIL
exit status 1
FAIL    test    0.002s

It needs to be the full path:

% TMPDIR=/home/martin/testtmp/tmp go test
/home/martin/testtmp/tmp/TestTest2010017600/001
/home/martin/testtmp/tmp/TestTest2010017600/002
/home/martin/testtmp/tmp/TestTest2010017600/003
PASS
ok      test    0.002s

---

Context: I have some filesystem-specific code that's sensitive to the current directory, so I need to change it. I have ./tmp mounted as a XFS image to test that it works on that, in addition to ext4.

I can just use the full path of course, but it's fairly long and annoying, and "it works fine, except in this one specific case" is rather confusing. And should be easy enough to fix with filepath.Abs() call.

[gabyhelp]

Similar Issues

• cmd/go: can't handle relative TMPDIR #23264
• os: TempDir() returns path without validation #19695
• testing: test failes if leaving files without write permission in T.TempDir #40853
• testing: T.TempDir does not clean illegal characters correctly on Go 1.16.13 #50644
• testing: use $GOTMPDIR for temporary files when set #61585

_{(Emoji vote if this was helpful or unhelpful; more detailed feedback welcome in this discussion.)}

[seankhliao]

I'd say this is working as intended. You want TMPDIR to be relative to the current directory, and it stays relative to your working directory.

TMPDIR=$(pwd)/tmp isn't that much to type out.