1 files changed, 506 insertions, 0 deletions
diff --git a/src/internal/testenv/testenv.go b/src/internal/testenv/testenv.go
new file mode 100644
index 0000000..5c80137
--- /dev/null
+++ b/src/internal/testenv/testenv.go
@@ -0,0 +1,506 @@
+// Copyright 2015 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 provides information about what functionality
+// is available in different testing environments run by the Go team.
+//
+// It is an internal package because these details are specific
+// to the Go team's test setup (on build.golang.org) and not
+// fundamental to tests in general.
+package testenv
+
+import (
+	"bytes"
+	"errors"
+	"flag"
+	"fmt"
+	"internal/cfg"
+	"internal/platform"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"runtime"
+	"strconv"
+	"strings"
+	"sync"
+	"testing"
+)
+
+// Save the original environment during init for use in checks. A test
+// binary may modify its environment before calling HasExec to change its
+// behavior (such as mimicking a command-line tool), and that modified
+// environment might cause environment checks to behave erratically.
+var origEnv = os.Environ()
+
+// Builder reports the name of the builder running this test
+// (for example, "linux-amd64" or "windows-386-gce").
+// If the test is not running on the build infrastructure,
+// Builder returns the empty string.
+func Builder() string {
+	return os.Getenv("GO_BUILDER_NAME")
+}
+
+// HasGoBuild reports whether the current system can build programs with “go build”
+// and then run them with os.StartProcess or exec.Command.
+func HasGoBuild() bool {
+	if os.Getenv("GO_GCFLAGS") != "" {
+		// It's too much work to require every caller of the go command
+		// to pass along "-gcflags="+os.Getenv("GO_GCFLAGS").
+		// For now, if $GO_GCFLAGS is set, report that we simply can't
+		// run go build.
+		return false
+	}
+
+	goBuildOnce.Do(func() {
+		// To run 'go build', we need to be able to exec a 'go' command.
+		// We somewhat arbitrarily choose to exec 'go tool -n compile' because that
+		// also confirms that cmd/go can find the compiler. (Before CL 472096,
+		// we sometimes ended up with cmd/go installed in the test environment
+		// without a cmd/compile it could use to actually build things.)
+		cmd := exec.Command("go", "tool", "-n", "compile")
+		cmd.Env = origEnv
+		out, err := cmd.Output()
+		if err != nil {
+			goBuildErr = fmt.Errorf("%v: %w", cmd, err)
+			return
+		}
+		out = bytes.TrimSpace(out)
+		if len(out) == 0 {
+			goBuildErr = fmt.Errorf("%v: no tool reported", cmd)
+			return
+		}
+		if _, err := exec.LookPath(string(out)); err != nil {
+			goBuildErr = err
+			return
+		}
+
+		if platform.MustLinkExternal(runtime.GOOS, runtime.GOARCH, false) {
+			// We can assume that we always have a complete Go toolchain available.
+			// However, this platform requires a C linker to build even pure Go
+			// programs, including tests. Do we have one in the test environment?
+			// (On Android, for example, the device running the test might not have a
+			// C toolchain installed.)
+			//
+			// If CC is set explicitly, assume that we do. Otherwise, use 'go env CC'
+			// to determine which toolchain it would use by default.
+			if os.Getenv("CC") == "" {
+				cmd := exec.Command("go", "env", "CC")
+				cmd.Env = origEnv
+				out, err := cmd.Output()
+				if err != nil {
+					goBuildErr = fmt.Errorf("%v: %w", cmd, err)
+					return
+				}
+				out = bytes.TrimSpace(out)
+				if len(out) == 0 {
+					goBuildErr = fmt.Errorf("%v: no CC reported", cmd)
+					return
+				}
+				_, goBuildErr = exec.LookPath(string(out))
+			}
+		}
+	})
+
+	return goBuildErr == nil
+}
+
+var (
+	goBuildOnce sync.Once
+	goBuildErr  error
+)
+
+// MustHaveGoBuild checks that the current system can build programs with “go build”
+// and then run them with os.StartProcess or exec.Command.
+// If not, MustHaveGoBuild calls t.Skip with an explanation.
+func MustHaveGoBuild(t testing.TB) {
+	if os.Getenv("GO_GCFLAGS") != "" {
+		t.Helper()
+		t.Skipf("skipping test: 'go build' not compatible with setting $GO_GCFLAGS")
+	}
+	if !HasGoBuild() {
+		t.Helper()
+		t.Skipf("skipping test: 'go build' unavailable: %v", goBuildErr)
+	}
+}
+
+// HasGoRun reports whether the current system can run programs with “go run”.
+func HasGoRun() bool {
+	// For now, having go run and having go build are the same.
+	return HasGoBuild()
+}
+
+// MustHaveGoRun checks that the current system can run programs with “go run”.
+// If not, MustHaveGoRun calls t.Skip with an explanation.
+func MustHaveGoRun(t testing.TB) {
+	if !HasGoRun() {
+		t.Skipf("skipping test: 'go run' not available on %s/%s", runtime.GOOS, runtime.GOARCH)
+	}
+}
+
+// HasParallelism reports whether the current system can execute multiple
+// threads in parallel.
+// There is a copy of this function in cmd/dist/test.go.
+func HasParallelism() bool {
+	switch runtime.GOOS {
+	case "js", "wasip1":
+		return false
+	}
+	return true
+}
+
+// MustHaveParallelism checks that the current system can execute multiple
+// threads in parallel. If not, MustHaveParallelism calls t.Skip with an explanation.
+func MustHaveParallelism(t testing.TB) {
+	if !HasParallelism() {
+		t.Skipf("skipping test: no parallelism available on %s/%s", runtime.GOOS, runtime.GOARCH)
+	}
+}
+
+// GoToolPath reports the path to the Go tool.
+// It is a convenience wrapper around GoTool.
+// If the tool is unavailable GoToolPath calls t.Skip.
+// If the tool should be available and isn't, GoToolPath calls t.Fatal.
+func GoToolPath(t testing.TB) string {
+	MustHaveGoBuild(t)
+	path, err := GoTool()
+	if err != nil {
+		t.Fatal(err)
+	}
+	// Add all environment variables that affect the Go command to test metadata.
+	// Cached test results will be invalidate when these variables change.
+	// See golang.org/issue/32285.
+	for _, envVar := range strings.Fields(cfg.KnownEnv) {
+		os.Getenv(envVar)
+	}
+	return path
+}
+
+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, or explicitly set GOROOT_FINAL but not GOROOT
+			// and hasn't moved the tree to GOROOT_FINAL yet. But those cases are
+			// rare, and if that happens the user can fix what they broke.)
+			return
+		}
+
+		// runtime.GOROOT doesn't know where GOROOT is (perhaps because the test
+		// binary was built with -trimpath, or perhaps because GOROOT_FINAL was set
+		// without GOROOT and the tree hasn't been moved there yet).
+		//
+		// Since this is internal/testenv, we can cheat and assume that the caller
+		// is a test of some package in a subdirectory of GOROOT/src. ('go test'
+		// runs the test in the directory containing the packaged under test.) That
+		// means that if we start walking up the tree, we should eventually find
+		// GOROOT/src/go.mod, and we can report the parent directory of that.
+		//
+		// Notably, this works even if we can't run 'go env GOROOT' as a
+		// subprocess.
+
+		cwd, err := os.Getwd()
+		if err != nil {
+			gorootErr = fmt.Errorf("finding GOROOT: %w", err)
+			return
+		}
+
+		dir := cwd
+		for {
+			parent := filepath.Dir(dir)
+			if parent == dir {
+				// dir is either "." or only a volume name.
+				gorootErr = fmt.Errorf("failed to locate GOROOT/src in any parent directory")
+				return
+			}
+
+			if base := filepath.Base(dir); base != "src" {
+				dir = parent
+				continue // dir cannot be GOROOT/src if it doesn't end in "src".
+			}
+
+			b, err := os.ReadFile(filepath.Join(dir, "go.mod"))
+			if err != nil {
+				if os.IsNotExist(err) {
+					dir = parent
+					continue
+				}
+				gorootErr = fmt.Errorf("finding GOROOT: %w", err)
+				return
+			}
+			goMod := string(b)
+
+			for goMod != "" {
+				var line string
+				line, goMod, _ = strings.Cut(goMod, "\n")
+				fields := strings.Fields(line)
+				if len(fields) >= 2 && fields[0] == "module" && fields[1] == "std" {
+					// Found "module std", which is the module declaration in GOROOT/src!
+					gorootPath = parent
+					return
+				}
+			}
+		}
+	})
+
+	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 and cannot exec
+// 'go env GOROOT'.
+//
+// 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
+}
+
+// GoTool reports the path to the Go tool.
+func GoTool() (string, error) {
+	if !HasGoBuild() {
+		return "", errors.New("platform cannot run go tool")
+	}
+	goToolOnce.Do(func() {
+		goToolPath, goToolErr = exec.LookPath("go")
+	})
+	return goToolPath, goToolErr
+}
+
+var (
+	goToolOnce sync.Once
+	goToolPath string
+	goToolErr  error
+)
+
+// HasSrc reports whether the entire source tree is available under GOROOT.
+func HasSrc() bool {
+	switch runtime.GOOS {
+	case "ios":
+		return false
+	}
+	return true
+}
+
+// HasExternalNetwork reports whether the current system can use
+// external (non-localhost) networks.
+func HasExternalNetwork() bool {
+	return !testing.Short() && runtime.GOOS != "js" && runtime.GOOS != "wasip1"
+}
+
+// MustHaveExternalNetwork checks that the current system can use
+// external (non-localhost) networks.
+// If not, MustHaveExternalNetwork calls t.Skip with an explanation.
+func MustHaveExternalNetwork(t testing.TB) {
+	if runtime.GOOS == "js" || runtime.GOOS == "wasip1" {
+		t.Helper()
+		t.Skipf("skipping test: no external network on %s", runtime.GOOS)
+	}
+	if testing.Short() {
+		t.Helper()
+		t.Skipf("skipping test: no external network in -short mode")
+	}
+}
+
+// HasCGO reports whether the current system can use cgo.
+func HasCGO() bool {
+	hasCgoOnce.Do(func() {
+		goTool, err := GoTool()
+		if err != nil {
+			return
+		}
+		cmd := exec.Command(goTool, "env", "CGO_ENABLED")
+		cmd.Env = origEnv
+		out, err := cmd.Output()
+		if err != nil {
+			panic(fmt.Sprintf("%v: %v", cmd, out))
+		}
+		hasCgo, err = strconv.ParseBool(string(bytes.TrimSpace(out)))
+		if err != nil {
+			panic(fmt.Sprintf("%v: non-boolean output %q", cmd, out))
+		}
+	})
+	return hasCgo
+}
+
+var (
+	hasCgoOnce sync.Once
+	hasCgo     bool
+)
+
+// MustHaveCGO calls t.Skip if cgo is not available.
+func MustHaveCGO(t testing.TB) {
+	if !HasCGO() {
+		t.Skipf("skipping test: no cgo")
+	}
+}
+
+// CanInternalLink reports whether the current system can link programs with
+// internal linking.
+func CanInternalLink(withCgo bool) bool {
+	return !platform.MustLinkExternal(runtime.GOOS, runtime.GOARCH, withCgo)
+}
+
+// MustInternalLink checks that the current system can link programs with internal
+// linking.
+// If not, MustInternalLink calls t.Skip with an explanation.
+func MustInternalLink(t testing.TB, withCgo bool) {
+	if !CanInternalLink(withCgo) {
+		if withCgo && CanInternalLink(false) {
+			t.Skipf("skipping test: internal linking on %s/%s is not supported with cgo", runtime.GOOS, runtime.GOARCH)
+		}
+		t.Skipf("skipping test: internal linking on %s/%s is not supported", runtime.GOOS, runtime.GOARCH)
+	}
+}
+
+// MustHaveBuildMode reports whether the current system can build programs in
+// the given build mode.
+// If not, MustHaveBuildMode calls t.Skip with an explanation.
+func MustHaveBuildMode(t testing.TB, buildmode string) {
+	if !platform.BuildModeSupported(runtime.Compiler, buildmode, runtime.GOOS, runtime.GOARCH) {
+		t.Skipf("skipping test: build mode %s on %s/%s is not supported by the %s compiler", buildmode, runtime.GOOS, runtime.GOARCH, runtime.Compiler)
+	}
+}
+
+// HasSymlink reports whether the current system can use os.Symlink.
+func HasSymlink() bool {
+	ok, _ := hasSymlink()
+	return ok
+}
+
+// MustHaveSymlink reports whether the current system can use os.Symlink.
+// If not, MustHaveSymlink calls t.Skip with an explanation.
+func MustHaveSymlink(t testing.TB) {
+	ok, reason := hasSymlink()
+	if !ok {
+		t.Skipf("skipping test: cannot make symlinks on %s/%s: %s", runtime.GOOS, runtime.GOARCH, reason)
+	}
+}
+
+// HasLink reports whether the current system can use os.Link.
+func HasLink() bool {
+	// From Android release M (Marshmallow), hard linking files is blocked
+	// and an attempt to call link() on a file will return EACCES.
+	// - https://code.google.com/p/android-developer-preview/issues/detail?id=3150
+	return runtime.GOOS != "plan9" && runtime.GOOS != "android"
+}
+
+// MustHaveLink reports whether the current system can use os.Link.
+// If not, MustHaveLink calls t.Skip with an explanation.
+func MustHaveLink(t testing.TB) {
+	if !HasLink() {
+		t.Skipf("skipping test: hardlinks are not supported on %s/%s", runtime.GOOS, runtime.GOARCH)
+	}
+}
+
+var flaky = flag.Bool("flaky", false, "run known-flaky tests too")
+
+func SkipFlaky(t testing.TB, issue int) {
+	t.Helper()
+	if !*flaky {
+		t.Skipf("skipping known flaky test without the -flaky flag; see golang.org/issue/%d", issue)
+	}
+}
+
+func SkipFlakyNet(t testing.TB) {
+	t.Helper()
+	if v, _ := strconv.ParseBool(os.Getenv("GO_BUILDER_FLAKY_NET")); v {
+		t.Skip("skipping test on builder known to have frequent network failures")
+	}
+}
+
+// CPUIsSlow reports whether the CPU running the test is suspected to be slow.
+func CPUIsSlow() bool {
+	switch runtime.GOARCH {
+	case "arm", "mips", "mipsle", "mips64", "mips64le", "wasm":
+		return true
+	}
+	return false
+}
+
+// SkipIfShortAndSlow skips t if -short is set and the CPU running the test is
+// suspected to be slow.
+//
+// (This is useful for CPU-intensive tests that otherwise complete quickly.)
+func SkipIfShortAndSlow(t testing.TB) {
+	if testing.Short() && CPUIsSlow() {
+		t.Helper()
+		t.Skipf("skipping test in -short mode on %s", runtime.GOARCH)
+	}
+}
+
+// SkipIfOptimizationOff skips t if optimization is disabled.
+func SkipIfOptimizationOff(t testing.TB) {
+	if OptimizationOff() {
+		t.Helper()
+		t.Skip("skipping test with optimization disabled")
+	}
+}
+
+// WriteImportcfg writes an importcfg file used by the compiler or linker to
+// dstPath containing entries for the file mappings in packageFiles, as well
+// as for the packages transitively imported by the package(s) in pkgs.
+//
+// pkgs may include any package pattern that is valid to pass to 'go list',
+// so it may also be a list of Go source files all in the same directory.
+func WriteImportcfg(t testing.TB, dstPath string, packageFiles map[string]string, pkgs ...string) {
+	t.Helper()
+
+	icfg := new(bytes.Buffer)
+	icfg.WriteString("# import config\n")
+	for k, v := range packageFiles {
+		fmt.Fprintf(icfg, "packagefile %s=%s\n", k, v)
+	}
+
+	if len(pkgs) > 0 {
+		// Use 'go list' to resolve any missing packages and rewrite the import map.
+		cmd := Command(t, GoToolPath(t), "list", "-export", "-deps", "-f", `{{if ne .ImportPath "command-line-arguments"}}{{if .Export}}{{.ImportPath}}={{.Export}}{{end}}{{end}}`)
+		cmd.Args = append(cmd.Args, pkgs...)
+		cmd.Stderr = new(strings.Builder)
+		out, err := cmd.Output()
+		if err != nil {
+			t.Fatalf("%v: %v\n%s", cmd, err, cmd.Stderr)
+		}
+
+		for _, line := range strings.Split(string(out), "\n") {
+			if line == "" {
+				continue
+			}
+			importPath, export, ok := strings.Cut(line, "=")
+			if !ok {
+				t.Fatalf("invalid line in output from %v:\n%s", cmd, line)
+			}
+			if packageFiles[importPath] == "" {
+				fmt.Fprintf(icfg, "packagefile %s=%s\n", importPath, export)
+			}
+		}
+	}
+
+	if err := os.WriteFile(dstPath, icfg.Bytes(), 0666); err != nil {
+		t.Fatal(err)
+	}
+}
+
+// SyscallIsNotSupported reports whether err may indicate that a system call is
+// not supported by the current platform or execution environment.
+func SyscallIsNotSupported(err error) bool {
+	return syscallIsNotSupported(err)
+}