1 files changed, 259 insertions, 0 deletions
diff --git a/src/cmd/internal/script/scripttest/run.go b/src/cmd/internal/script/scripttest/run.go
new file mode 100644
index 0000000000..d2f3ed8ca9
--- /dev/null
+++ b/src/cmd/internal/script/scripttest/run.go
@@ -0,0 +1,259 @@
+// Copyright 2022 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 scripttest adapts the script engine for use in tests.
+package scripttest
+
+import (
+	"bytes"
+	"cmd/internal/script"
+	"context"
+	"fmt"
+	"internal/testenv"
+	"internal/txtar"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"runtime"
+	"strings"
+	"testing"
+	"time"
+)
+
+// ToolReplacement records the name of a tool to replace
+// within a given GOROOT for script testing purposes.
+type ToolReplacement struct {
+	ToolName        string // e.g. compile, link, addr2line, etc
+	ReplacementPath string // path to replacement tool exe
+	EnvVar          string // env var setting (e.g. "FOO=BAR")
+}
+
+// RunToolScriptTest kicks off a set of script tests runs for
+// a tool of some sort (compiler, linker, etc). The expectation
+// is that we'll be called from the top level cmd/X dir for tool X,
+// and that instead of executing the install tool X we'll use the
+// test binary instead.
+func RunToolScriptTest(t *testing.T, repls []ToolReplacement, pattern string) {
+	// Nearly all script tests involve doing builds, so don't
+	// bother here if we don't have "go build".
+	testenv.MustHaveGoBuild(t)
+
+	// Skip this path on plan9, which doesn't support symbolic
+	// links (we would have to copy too much).
+	if runtime.GOOS == "plan9" {
+		t.Skipf("no symlinks on plan9")
+	}
+
+	// Locate our Go tool.
+	gotool, err := testenv.GoTool()
+	if err != nil {
+		t.Fatalf("locating go tool: %v", err)
+	}
+
+	goEnv := func(name string) string {
+		out, err := exec.Command(gotool, "env", name).CombinedOutput()
+		if err != nil {
+			t.Fatalf("go env %s: %v\n%s", name, err, out)
+		}
+		return strings.TrimSpace(string(out))
+	}
+
+	// Construct an initial set of commands + conditions to make available
+	// to the script tests.
+	cmds := DefaultCmds()
+	conds := DefaultConds()
+
+	addcmd := func(name string, cmd script.Cmd) {
+		if _, ok := cmds[name]; ok {
+			panic(fmt.Sprintf("command %q is already registered", name))
+		}
+		cmds[name] = cmd
+	}
+
+	addcond := func(name string, cond script.Cond) {
+		if _, ok := conds[name]; ok {
+			panic(fmt.Sprintf("condition %q is already registered", name))
+		}
+		conds[name] = cond
+	}
+
+	prependToPath := func(env []string, dir string) {
+		found := false
+		for k := range env {
+			ev := env[k]
+			if !strings.HasPrefix(ev, "PATH=") {
+				continue
+			}
+			oldpath := ev[5:]
+			env[k] = "PATH=" + dir + string(filepath.ListSeparator) + oldpath
+			found = true
+			break
+		}
+		if !found {
+			t.Fatalf("could not update PATH")
+		}
+	}
+
+	setenv := func(env []string, varname, val string) []string {
+		pref := varname + "="
+		found := false
+		for k := range env {
+			if !strings.HasPrefix(env[k], pref) {
+				continue
+			}
+			env[k] = pref + val
+			found = true
+			break
+		}
+		if !found {
+			env = append(env, varname+"="+val)
+		}
+		return env
+	}
+
+	interrupt := func(cmd *exec.Cmd) error {
+		return cmd.Process.Signal(os.Interrupt)
+	}
+	gracePeriod := 60 * time.Second // arbitrary
+
+	// Set up an alternate go root for running script tests, since it
+	// is possible that we might want to replace one of the installed
+	// tools with a unit test executable.
+	goroot := goEnv("GOROOT")
+	tmpdir := t.TempDir()
+	tgr := SetupTestGoRoot(t, tmpdir, goroot)
+
+	// Replace tools if appropriate
+	for _, repl := range repls {
+		ReplaceGoToolInTestGoRoot(t, tgr, repl.ToolName, repl.ReplacementPath)
+	}
+
+	// Add in commands for "go" and "cc".
+	testgo := filepath.Join(tgr, "bin", "go")
+	gocmd := script.Program(testgo, interrupt, gracePeriod)
+	cccmd := script.Program(goEnv("CC"), interrupt, gracePeriod)
+	addcmd("go", gocmd)
+	addcmd("cc", cccmd)
+	addcond("cgo", script.BoolCondition("host CGO_ENABLED", testenv.HasCGO()))
+
+	// Environment setup.
+	env := os.Environ()
+	prependToPath(env, filepath.Join(tgr, "bin"))
+	env = setenv(env, "GOROOT", tgr)
+	for _, repl := range repls {
+		// consistency check
+		chunks := strings.Split(repl.EnvVar, "=")
+		if len(chunks) != 2 {
+			t.Fatalf("malformed env var setting: %s", repl.EnvVar)
+		}
+		env = append(env, repl.EnvVar)
+	}
+
+	// Manufacture engine...
+	engine := &script.Engine{
+		Conds: conds,
+		Cmds:  cmds,
+		Quiet: !testing.Verbose(),
+	}
+
+	// ... and kick off tests.
+	ctx := context.Background()
+	RunTests(t, ctx, engine, env, pattern)
+}
+
+// RunTests kicks off one or more script-based tests using the
+// specified engine, running all test files that match pattern.
+// This function adapted from Russ's rsc.io/script/scripttest#Run
+// function, which was in turn forked off cmd/go's runner.
+func RunTests(t *testing.T, ctx context.Context, engine *script.Engine, env []string, pattern string) {
+	gracePeriod := 100 * time.Millisecond
+	if deadline, ok := t.Deadline(); ok {
+		timeout := time.Until(deadline)
+
+		// If time allows, increase the termination grace period to 5% of the
+		// remaining time.
+		if gp := timeout / 20; gp > gracePeriod {
+			gracePeriod = gp
+		}
+
+		// When we run commands that execute subprocesses, we want to
+		// reserve two grace periods to clean up. We will send the
+		// first termination signal when the context expires, then
+		// wait one grace period for the process to produce whatever
+		// useful output it can (such as a stack trace). After the
+		// first grace period expires, we'll escalate to os.Kill,
+		// leaving the second grace period for the test function to
+		// record its output before the test process itself
+		// terminates.
+		timeout -= 2 * gracePeriod
+
+		var cancel context.CancelFunc
+		ctx, cancel = context.WithTimeout(ctx, timeout)
+		t.Cleanup(cancel)
+	}
+
+	files, _ := filepath.Glob(pattern)
+	if len(files) == 0 {
+		t.Fatal("no testdata")
+	}
+	for _, file := range files {
+		file := file
+		name := strings.TrimSuffix(filepath.Base(file), ".txt")
+		t.Run(name, func(t *testing.T) {
+			t.Parallel()
+
+			workdir := t.TempDir()
+			s, err := script.NewState(ctx, workdir, env)
+			if err != nil {
+				t.Fatal(err)
+			}
+
+			// Unpack archive.
+			a, err := txtar.ParseFile(file)
+			if err != nil {
+				t.Fatal(err)
+			}
+			initScriptDirs(t, s)
+			if err := s.ExtractFiles(a); err != nil {
+				t.Fatal(err)
+			}
+
+			t.Log(time.Now().UTC().Format(time.RFC3339))
+			work, _ := s.LookupEnv("WORK")
+			t.Logf("$WORK=%s", work)
+
+			// Note: Do not use filepath.Base(file) here:
+			// editors that can jump to file:line references in the output
+			// will work better seeing the full path relative to the
+			// directory containing the command being tested
+			// (e.g. where "go test" command is usually run).
+			Run(t, engine, s, file, bytes.NewReader(a.Comment))
+		})
+	}
+}
+
+func initScriptDirs(t testing.TB, s *script.State) {
+	must := func(err error) {
+		if err != nil {
+			t.Helper()
+			t.Fatal(err)
+		}
+	}
+
+	work := s.Getwd()
+	must(s.Setenv("WORK", work))
+	must(os.MkdirAll(filepath.Join(work, "tmp"), 0777))
+	must(s.Setenv(tempEnvName(), filepath.Join(work, "tmp")))
+}
+
+func tempEnvName() string {
+	switch runtime.GOOS {
+	case "windows":
+		return "TMP"
+	case "plan9":
+		return "TMPDIR" // actually plan 9 doesn't have one at all but this is fine
+	default:
+		return "TMPDIR"
+	}
+}