internal/testenv/testenv.go - tools - Git at Google

 // Copyright 2019 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.

 // Package testenv contains helper functions for skipping tests
 // based on which tools are present in the environment.
 package testenv

 import (
 	"bytes"
 	"fmt"
 	"go/build"
 	"io/ioutil"
 	"os"
 	"runtime"
 	"runtime/debug"
 	"strings"
 	"sync"
 	"testing"
 	"time"

 	"golang.org/x/tools/internal/goroot"

 	exec "golang.org/x/sys/execabs"
 )

 // packageMainIsDevel reports whether the module containing package main
 // is a development version (if module information is available).
 func packageMainIsDevel() bool {
 	info, ok := debug.ReadBuildInfo()
 	if !ok {
 		// Most test binaries currently lack build info, but this should become more
 		// permissive once https://golang.org/issue/33976 is fixed.
 		return true
 	}

 	// Note: info.Main.Version describes the version of the module containing
 	// package main, not the version of “the main module”.
 	// See https://golang.org/issue/33975.
 	return info.Main.Version == "(devel)"
 }

 var checkGoGoroot struct {
 	once sync.Once
 	err  error
 }

 func hasTool(tool string) error {
 	if tool == "cgo" {
 		enabled, err := cgoEnabled(false)
 		if err != nil {
 			return fmt.Errorf("checking cgo: %v", err)
 		}
 		if !enabled {
 			return fmt.Errorf("cgo not enabled")
 		}
 		return nil
 	}

 	_, err := exec.LookPath(tool)
 	if err != nil {
 		return err
 	}

 	switch tool {
 	case "patch":
 		// check that the patch tools supports the -o argument
 		temp, err := ioutil.TempFile("", "patch-test")
 		if err != nil {
 			return err
 		}
 		temp.Close()
 		defer os.Remove(temp.Name())
 		cmd := exec.Command(tool, "-o", temp.Name())
 		if err := cmd.Run(); err != nil {
 			return err
 		}

 	case "go":
 		checkGoGoroot.once.Do(func() {
 			// Ensure that the 'go' command found by exec.LookPath is from the correct
 			// GOROOT. Otherwise, 'some/path/go test ./...' will test against some
 			// version of the 'go' binary other than 'some/path/go', which is almost
 			// certainly not what the user intended.
 			out, err := exec.Command(tool, "env", "GOROOT").CombinedOutput()
 			if err != nil {
 				checkGoGoroot.err = err
 				return
 			}
 			GOROOT := strings.TrimSpace(string(out))
 			if GOROOT != runtime.GOROOT() {
 				checkGoGoroot.err = fmt.Errorf("'go env GOROOT' does not match runtime.GOROOT:\n\tgo env: %s\n\tGOROOT: %s", GOROOT, runtime.GOROOT())
 				return
 			}

 			// Also ensure that that GOROOT includes a compiler: 'go' commands
 			// don't in general work without it, and some builders
 			// (such as android-amd64-emu) seem to lack it in the test environment.
 			cmd := exec.Command(tool, "tool", "-n", "compile")
 			stderr := new(bytes.Buffer)
 			stderr.Write([]byte("\n"))
 			cmd.Stderr = stderr
 			out, err = cmd.Output()
 			if err != nil {
 				checkGoGoroot.err = fmt.Errorf("%v: %v%s", cmd, err, stderr)
 				return
 			}
 			if _, err := os.Stat(string(bytes.TrimSpace(out))); err != nil {
 				checkGoGoroot.err = err
 			}
 		})
 		if checkGoGoroot.err != nil {
 			return checkGoGoroot.err
 		}

 	case "diff":
 		// Check that diff is the GNU version, needed for the -u argument and
 		// to report missing newlines at the end of files.
 		out, err := exec.Command(tool, "-version").Output()
 		if err != nil {
 			return err
 		}
 		if !bytes.Contains(out, []byte("GNU diffutils")) {
 			return fmt.Errorf("diff is not the GNU version")
 		}
 	}

 	return nil
 }

 func cgoEnabled(bypassEnvironment bool) (bool, error) {
 	cmd := exec.Command("go", "env", "CGO_ENABLED")
 	if bypassEnvironment {
 		cmd.Env = append(append([]string(nil), os.Environ()...), "CGO_ENABLED=")
 	}
 	out, err := cmd.CombinedOutput()
 	if err != nil {
 		return false, err
 	}
 	enabled := strings.TrimSpace(string(out))
 	return enabled == "1", nil
 }

 func allowMissingTool(tool string) bool {
 	if runtime.GOOS == "android" {
 		// Android builds generally run tests on a separate machine from the build,
 		// so don't expect any external tools to be available.
 		return true
 	}

 	switch tool {
 	case "cgo":
 		if strings.HasSuffix(os.Getenv("GO_BUILDER_NAME"), "-nocgo") {
 			// Explicitly disabled on -nocgo builders.
 			return true
 		}
 		if enabled, err := cgoEnabled(true); err == nil && !enabled {
 			// No platform support.
 			return true
 		}
 	case "go":
 		if os.Getenv("GO_BUILDER_NAME") == "illumos-amd64-joyent" {
 			// Work around a misconfigured builder (see https://golang.org/issue/33950).
 			return true
 		}
 	case "diff":
 		if os.Getenv("GO_BUILDER_NAME") != "" {
 			return true
 		}
 	case "patch":
 		if os.Getenv("GO_BUILDER_NAME") != "" {
 			return true
 		}
 	}

 	// If a developer is actively working on this test, we expect them to have all
 	// of its dependencies installed. However, if it's just a dependency of some
 	// other module (for example, being run via 'go test all'), we should be more
 	// tolerant of unusual environments.
 	return !packageMainIsDevel()
 }

 // NeedsTool skips t if the named tool is not present in the path.
 // As a special case, "cgo" means "go" is present and can compile cgo programs.
 func NeedsTool(t testing.TB, tool string) {
 	err := hasTool(tool)
 	if err == nil {
 		return
 	}

 	t.Helper()
 	if allowMissingTool(tool) {
 		t.Skipf("skipping because %s tool not available: %v", tool, err)
 	} else {
 		t.Fatalf("%s tool not available: %v", tool, err)
 	}
 }

 // NeedsGoPackages skips t if the go/packages driver (or 'go' tool) implied by
 // the current process environment is not present in the path.
 func NeedsGoPackages(t testing.TB) {
 	t.Helper()

 	tool := os.Getenv("GOPACKAGESDRIVER")
 	switch tool {
 	case "off":
 		// "off" forces go/packages to use the go command.
 		tool = "go"
 	case "":
 		if _, err := exec.LookPath("gopackagesdriver"); err == nil {
 			tool = "gopackagesdriver"
 		} else {
 			tool = "go"
 		}
 	}

 	NeedsTool(t, tool)
 }

 // NeedsGoPackagesEnv skips t if the go/packages driver (or 'go' tool) implied
 // by env is not present in the path.
 func NeedsGoPackagesEnv(t testing.TB, env []string) {
 	t.Helper()

 	for _, v := range env {
 		if strings.HasPrefix(v, "GOPACKAGESDRIVER=") {
 			tool := strings.TrimPrefix(v, "GOPACKAGESDRIVER=")
 			if tool == "off" {
 				NeedsTool(t, "go")
 			} else {
 				NeedsTool(t, tool)
 			}
 			return
 		}
 	}

 	NeedsGoPackages(t)
 }

 // NeedsGoBuild skips t if the current system can't build programs with “go build”
 // and then run them with os.StartProcess or exec.Command.
 // Android doesn't have the userspace go build needs to run,
 // and js/wasm doesn't support running subprocesses.
 func NeedsGoBuild(t testing.TB) {
 	t.Helper()

 	// This logic was derived from internal/testing.HasGoBuild and
 	// may need to be updated as that function evolves.

 	NeedsTool(t, "go")

 	switch runtime.GOOS {
 	case "android", "js":
 		t.Skipf("skipping test: %v can't build and run Go binaries", runtime.GOOS)
 	}
 }

 // ExitIfSmallMachine emits a helpful diagnostic and calls os.Exit(0) if the
 // current machine is a builder known to have scarce resources.
 //
 // It should be called from within a TestMain function.
 func ExitIfSmallMachine() {
 	switch b := os.Getenv("GO_BUILDER_NAME"); b {
 	case "linux-arm-scaleway":
 		// "linux-arm" was renamed to "linux-arm-scaleway" in CL 303230.
 		fmt.Fprintln(os.Stderr, "skipping test: linux-arm-scaleway builder lacks sufficient memory (https://golang.org/issue/32834)")
 	case "plan9-arm":
 		fmt.Fprintln(os.Stderr, "skipping test: plan9-arm builder lacks sufficient memory (https://golang.org/issue/38772)")
 	case "netbsd-arm-bsiegert", "netbsd-arm64-bsiegert":
 		// As of 2021-06-02, these builders are running with GO_TEST_TIMEOUT_SCALE=10,
 		// and there is only one of each. We shouldn't waste those scarce resources
 		// running very slow tests.
 		fmt.Fprintf(os.Stderr, "skipping test: %s builder is very slow\n", b)
 	case "dragonfly-amd64":
 		// As of 2021-11-02, this builder is running with GO_TEST_TIMEOUT_SCALE=2,
 		// and seems to have unusually slow disk performance.
 		fmt.Fprintln(os.Stderr, "skipping test: dragonfly-amd64 has slow disk (https://golang.org/issue/45216)")
 	case "linux-riscv64-unmatched":
 		// As of 2021-11-03, this builder is empirically not fast enough to run
 		// gopls tests. Ideally we should make the tests faster in short mode
 		// and/or fix them to not assume arbitrary deadlines.
 		// For now, we'll skip them instead.
 		fmt.Fprintf(os.Stderr, "skipping test: %s builder is too slow (https://golang.org/issue/49321)\n", b)
 	default:
 		return
 	}
 	os.Exit(0)
 }

 // Go1Point returns the x in Go 1.x.
 func Go1Point() int {
 	for i := len(build.Default.ReleaseTags) - 1; i >= 0; i-- {
 		var version int
 		if _, err := fmt.Sscanf(build.Default.ReleaseTags[i], "go1.%d", &version); err != nil {
 			continue
 		}
 		return version
 	}
 	panic("bad release tags")
 }

 // NeedsGo1Point skips t if the Go version used to run the test is older than
 // 1.x.
 func NeedsGo1Point(t testing.TB, x int) {
 	if Go1Point() < x {
 		t.Helper()
 		t.Skipf("running Go version %q is version 1.%d, older than required 1.%d", runtime.Version(), Go1Point(), x)
 	}
 }

 // SkipAfterGo1Point skips t if the Go version used to run the test is newer than
 // 1.x.
 func SkipAfterGo1Point(t testing.TB, x int) {
 	if Go1Point() > x {
 		t.Helper()
 		t.Skipf("running Go version %q is version 1.%d, newer than maximum 1.%d", runtime.Version(), Go1Point(), x)
 	}
 }

 // Deadline returns the deadline of t, if known,
 // using the Deadline method added in Go 1.15.
 func Deadline(t testing.TB) (time.Time, bool) {
 	td, ok := t.(interface {
 		Deadline() (time.Time, bool)
 	})
 	if !ok {
 		return time.Time{}, false
 	}
 	return td.Deadline()
 }

 // WriteImportcfg writes an importcfg file used by the compiler or linker to
 // dstPath containing entries for the packages in std and cmd in addition
 // to the package to package file mappings in additionalPackageFiles.
 func WriteImportcfg(t testing.TB, dstPath string, additionalPackageFiles map[string]string) {
 	importcfg, err := goroot.Importcfg()
 	for k, v := range additionalPackageFiles {
 		importcfg += fmt.Sprintf("\npackagefile %s=%s", k, v)
 	}
 	if err != nil {
 		t.Fatalf("preparing the importcfg failed: %s", err)
 	}
 	ioutil.WriteFile(dstPath, []byte(importcfg), 0655)
 	if err != nil {
 		t.Fatalf("writing the importcfg failed: %s", err)
 	}
 }

 var (
 	gorootOnce sync.Once
 	gorootPath string
 	gorootErr  error
 )

 func findGOROOT() (string, error) {
 	gorootOnce.Do(func() {
 		gorootPath = runtime.GOROOT()
 		if gorootPath != "" {
 			// If runtime.GOROOT() is non-empty, assume that it is valid. (It might
 			// not be: for example, the user may have explicitly set GOROOT
 			// to the wrong directory.)
 			return
 		}

 		cmd := exec.Command("go", "env", "GOROOT")
 		out, err := cmd.Output()
 		if err != nil {
 			gorootErr = fmt.Errorf("%v: %v", cmd, err)
 		}
 		gorootPath = strings.TrimSpace(string(out))
 	})

 	return gorootPath, gorootErr
 }

 // GOROOT reports the path to the directory containing the root of the Go
 // project source tree. This is normally equivalent to runtime.GOROOT, but
 // works even if the test binary was built with -trimpath.
 //
 // If GOROOT cannot be found, GOROOT skips t if t is non-nil,
 // or panics otherwise.
 func GOROOT(t testing.TB) string {
 	path, err := findGOROOT()
 	if err != nil {
 		if t == nil {
 			panic(err)
 		}
 		t.Helper()
 		t.Skip(err)
 	}
 	return path
 }
	// Copyright 2019 The Go Authors. All rights reserved.
	// Use of this source code is governed by a BSD-style
	// license that can be found in the LICENSE file.

	// Package testenv contains helper functions for skipping tests
	// based on which tools are present in the environment.
	package testenv

	import (
	"bytes"
	"fmt"
	"go/build"
	"io/ioutil"
	"os"
	"runtime"
	"runtime/debug"
	"strings"
	"sync"
	"testing"
	"time"

	"golang.org/x/tools/internal/goroot"

	exec "golang.org/x/sys/execabs"
	)

	// packageMainIsDevel reports whether the module containing package main
	// is a development version (if module information is available).
	func packageMainIsDevel() bool {
	info, ok := debug.ReadBuildInfo()
	if !ok {
	// Most test binaries currently lack build info, but this should become more
	// permissive once https://golang.org/issue/33976 is fixed.
	return true
	}

	// Note: info.Main.Version describes the version of the module containing
	// package main, not the version of “the main module”.
	// See https://golang.org/issue/33975.
	return info.Main.Version == "(devel)"
	}

	var checkGoGoroot struct {
	once sync.Once
	err error
	}

	func hasTool(tool string) error {
	if tool == "cgo" {
	enabled, err := cgoEnabled(false)
	if err != nil {
	return fmt.Errorf("checking cgo: %v", err)
	}
	if !enabled {
	return fmt.Errorf("cgo not enabled")
	}
	return nil
	}

	_, err := exec.LookPath(tool)
	if err != nil {
	return err
	}

	switch tool {
	case "patch":
	// check that the patch tools supports the -o argument
	temp, err := ioutil.TempFile("", "patch-test")
	if err != nil {
	return err
	}
	temp.Close()
	defer os.Remove(temp.Name())
	cmd := exec.Command(tool, "-o", temp.Name())
	if err := cmd.Run(); err != nil {
	return err
	}

	case "go":
	checkGoGoroot.once.Do(func() {
	// Ensure that the 'go' command found by exec.LookPath is from the correct
	// GOROOT. Otherwise, 'some/path/go test ./...' will test against some
	// version of the 'go' binary other than 'some/path/go', which is almost
	// certainly not what the user intended.
	out, err := exec.Command(tool, "env", "GOROOT").CombinedOutput()
	if err != nil {
	checkGoGoroot.err = err
	return
	}
	GOROOT := strings.TrimSpace(string(out))
	if GOROOT != runtime.GOROOT() {
	checkGoGoroot.err = fmt.Errorf("'go env GOROOT' does not match runtime.GOROOT:\n\tgo env: %s\n\tGOROOT: %s", GOROOT, runtime.GOROOT())
	return
	}

	// Also ensure that that GOROOT includes a compiler: 'go' commands
	// don't in general work without it, and some builders
	// (such as android-amd64-emu) seem to lack it in the test environment.
	cmd := exec.Command(tool, "tool", "-n", "compile")
	stderr := new(bytes.Buffer)
	stderr.Write([]byte("\n"))
	cmd.Stderr = stderr
	out, err = cmd.Output()
	if err != nil {
	checkGoGoroot.err = fmt.Errorf("%v: %v%s", cmd, err, stderr)
	return
	}
	if _, err := os.Stat(string(bytes.TrimSpace(out))); err != nil {
	checkGoGoroot.err = err
	}
	})
	if checkGoGoroot.err != nil {
	return checkGoGoroot.err
	}

	case "diff":
	// Check that diff is the GNU version, needed for the -u argument and
	// to report missing newlines at the end of files.
	out, err := exec.Command(tool, "-version").Output()
	if err != nil {
	return err
	}
	if !bytes.Contains(out, []byte("GNU diffutils")) {
	return fmt.Errorf("diff is not the GNU version")
	}
	}

	return nil
	}

	func cgoEnabled(bypassEnvironment bool) (bool, error) {
	cmd := exec.Command("go", "env", "CGO_ENABLED")
	if bypassEnvironment {
	cmd.Env = append(append([]string(nil), os.Environ()...), "CGO_ENABLED=")
	}
	out, err := cmd.CombinedOutput()
	if err != nil {
	return false, err
	}
	enabled := strings.TrimSpace(string(out))
	return enabled == "1", nil
	}

	func allowMissingTool(tool string) bool {
	if runtime.GOOS == "android" {
	// Android builds generally run tests on a separate machine from the build,
	// so don't expect any external tools to be available.
	return true
	}

	switch tool {
	case "cgo":
	if strings.HasSuffix(os.Getenv("GO_BUILDER_NAME"), "-nocgo") {
	// Explicitly disabled on -nocgo builders.
	return true
	}
	if enabled, err := cgoEnabled(true); err == nil && !enabled {
	// No platform support.
	return true
	}
	case "go":
	if os.Getenv("GO_BUILDER_NAME") == "illumos-amd64-joyent" {
	// Work around a misconfigured builder (see https://golang.org/issue/33950).
	return true
	}
	case "diff":
	if os.Getenv("GO_BUILDER_NAME") != "" {
	return true
	}
	case "patch":
	if os.Getenv("GO_BUILDER_NAME") != "" {
	return true
	}
	}

	// If a developer is actively working on this test, we expect them to have all
	// of its dependencies installed. However, if it's just a dependency of some
	// other module (for example, being run via 'go test all'), we should be more
	// tolerant of unusual environments.
	return !packageMainIsDevel()
	}

	// NeedsTool skips t if the named tool is not present in the path.
	// As a special case, "cgo" means "go" is present and can compile cgo programs.
	func NeedsTool(t testing.TB, tool string) {
	err := hasTool(tool)
	if err == nil {
	return
	}

	t.Helper()
	if allowMissingTool(tool) {
	t.Skipf("skipping because %s tool not available: %v", tool, err)
	} else {
	t.Fatalf("%s tool not available: %v", tool, err)
	}
	}

	// NeedsGoPackages skips t if the go/packages driver (or 'go' tool) implied by
	// the current process environment is not present in the path.
	func NeedsGoPackages(t testing.TB) {
	t.Helper()

	tool := os.Getenv("GOPACKAGESDRIVER")
	switch tool {
	case "off":
	// "off" forces go/packages to use the go command.
	tool = "go"
	case "":
	if _, err := exec.LookPath("gopackagesdriver"); err == nil {
	tool = "gopackagesdriver"
	} else {
	tool = "go"
	}
	}

	NeedsTool(t, tool)
	}

	// NeedsGoPackagesEnv skips t if the go/packages driver (or 'go' tool) implied
	// by env is not present in the path.
	func NeedsGoPackagesEnv(t testing.TB, env []string) {
	t.Helper()

	for _, v := range env {
	if strings.HasPrefix(v, "GOPACKAGESDRIVER=") {
	tool := strings.TrimPrefix(v, "GOPACKAGESDRIVER=")
	if tool == "off" {
	NeedsTool(t, "go")
	} else {
	NeedsTool(t, tool)
	}
	return
	}
	}

	NeedsGoPackages(t)
	}

	// NeedsGoBuild skips t if the current system can't build programs with “go build”
	// and then run them with os.StartProcess or exec.Command.
	// Android doesn't have the userspace go build needs to run,
	// and js/wasm doesn't support running subprocesses.
	func NeedsGoBuild(t testing.TB) {
	t.Helper()

	// This logic was derived from internal/testing.HasGoBuild and
	// may need to be updated as that function evolves.

	NeedsTool(t, "go")

	switch runtime.GOOS {
	case "android", "js":
	t.Skipf("skipping test: %v can't build and run Go binaries", runtime.GOOS)
	}
	}

	// ExitIfSmallMachine emits a helpful diagnostic and calls os.Exit(0) if the
	// current machine is a builder known to have scarce resources.
	//
	// It should be called from within a TestMain function.
	func ExitIfSmallMachine() {
	switch b := os.Getenv("GO_BUILDER_NAME"); b {
	case "linux-arm-scaleway":
	// "linux-arm" was renamed to "linux-arm-scaleway" in CL 303230.
	fmt.Fprintln(os.Stderr, "skipping test: linux-arm-scaleway builder lacks sufficient memory (https://golang.org/issue/32834)")
	case "plan9-arm":
	fmt.Fprintln(os.Stderr, "skipping test: plan9-arm builder lacks sufficient memory (https://golang.org/issue/38772)")
	case "netbsd-arm-bsiegert", "netbsd-arm64-bsiegert":
	// As of 2021-06-02, these builders are running with GO_TEST_TIMEOUT_SCALE=10,
	// and there is only one of each. We shouldn't waste those scarce resources
	// running very slow tests.
	fmt.Fprintf(os.Stderr, "skipping test: %s builder is very slow\n", b)
	case "dragonfly-amd64":
	// As of 2021-11-02, this builder is running with GO_TEST_TIMEOUT_SCALE=2,
	// and seems to have unusually slow disk performance.
	fmt.Fprintln(os.Stderr, "skipping test: dragonfly-amd64 has slow disk (https://golang.org/issue/45216)")
	case "linux-riscv64-unmatched":
	// As of 2021-11-03, this builder is empirically not fast enough to run
	// gopls tests. Ideally we should make the tests faster in short mode
	// and/or fix them to not assume arbitrary deadlines.
	// For now, we'll skip them instead.
	fmt.Fprintf(os.Stderr, "skipping test: %s builder is too slow (https://golang.org/issue/49321)\n", b)
	default:
	return
	}
	os.Exit(0)
	}

	// Go1Point returns the x in Go 1.x.
	func Go1Point() int {
	for i := len(build.Default.ReleaseTags) - 1; i >= 0; i-- {
	var version int
	if _, err := fmt.Sscanf(build.Default.ReleaseTags[i], "go1.%d", &version); err != nil {
	continue
	}
	return version
	}
	panic("bad release tags")
	}

	// NeedsGo1Point skips t if the Go version used to run the test is older than
	// 1.x.
	func NeedsGo1Point(t testing.TB, x int) {
	if Go1Point() < x {
	t.Helper()
	t.Skipf("running Go version %q is version 1.%d, older than required 1.%d", runtime.Version(), Go1Point(), x)
	}
	}

	// SkipAfterGo1Point skips t if the Go version used to run the test is newer than
	// 1.x.
	func SkipAfterGo1Point(t testing.TB, x int) {
	if Go1Point() > x {
	t.Helper()
	t.Skipf("running Go version %q is version 1.%d, newer than maximum 1.%d", runtime.Version(), Go1Point(), x)
	}
	}

	// Deadline returns the deadline of t, if known,
	// using the Deadline method added in Go 1.15.
	func Deadline(t testing.TB) (time.Time, bool) {
	td, ok := t.(interface {
	Deadline() (time.Time, bool)
	})
	if !ok {
	return time.Time{}, false
	}
	return td.Deadline()
	}

	// WriteImportcfg writes an importcfg file used by the compiler or linker to
	// dstPath containing entries for the packages in std and cmd in addition
	// to the package to package file mappings in additionalPackageFiles.
	func WriteImportcfg(t testing.TB, dstPath string, additionalPackageFiles map[string]string) {
	importcfg, err := goroot.Importcfg()
	for k, v := range additionalPackageFiles {
	importcfg += fmt.Sprintf("\npackagefile %s=%s", k, v)
	}
	if err != nil {
	t.Fatalf("preparing the importcfg failed: %s", err)
	}
	ioutil.WriteFile(dstPath, []byte(importcfg), 0655)
	if err != nil {
	t.Fatalf("writing the importcfg failed: %s", err)
	}
	}

	var (
	gorootOnce sync.Once
	gorootPath string
	gorootErr error
	)

	func findGOROOT() (string, error) {
	gorootOnce.Do(func() {
	gorootPath = runtime.GOROOT()
	if gorootPath != "" {
	// If runtime.GOROOT() is non-empty, assume that it is valid. (It might
	// not be: for example, the user may have explicitly set GOROOT
	// to the wrong directory.)
	return
	}

	cmd := exec.Command("go", "env", "GOROOT")
	out, err := cmd.Output()
	if err != nil {
	gorootErr = fmt.Errorf("%v: %v", cmd, err)
	}
	gorootPath = strings.TrimSpace(string(out))
	})

	return gorootPath, gorootErr
	}

	// GOROOT reports the path to the directory containing the root of the Go
	// project source tree. This is normally equivalent to runtime.GOROOT, but
	// works even if the test binary was built with -trimpath.
	//
	// If GOROOT cannot be found, GOROOT skips t if t is non-nil,
	// or panics otherwise.
	func GOROOT(t testing.TB) string {
	path, err := findGOROOT()
	if err != nil {
	if t == nil {
	panic(err)
	}
	t.Helper()
	t.Skip(err)
	}
	return path
	}