Dispose subprocess descendants after leader exit

internal/adapters/subprocess/run_test.go

@@ -6,10 +6,12 @@ import (
 	"errors"
 	"os"
 	"os/exec"
+	"os/signal"
 	"path/filepath"
 	"runtime"
 	"strconv"
 	"strings"
+	"syscall"
 	"testing"
 	"time"
 
@@ -747,6 +749,41 @@ func TestSubprocessHelper(t *testing.T) {
 		}
 		time.Sleep(10 * time.Second)
 		os.Exit(0)
+	case "leader-exit-retained", "leader-exit-redirected", "leader-fail-redirected":
+		descendant := exec.Command(os.Args[0], "-test.run=^TestSubprocessHelper$", "--", "descendant-after-release")
+		descendant.Env = append(os.Environ(), "GO_WANT_SUBPROCESS_HELPER=1")
+		if mode == "leader-exit-retained" {
+			descendant.Stdout = os.Stdout
+			descendant.Stderr = os.Stderr
+		}
+		if err := descendant.Start(); err != nil {
+			os.Exit(3)
+		}
+		if !helperFileAppeared(os.Getenv("SUBPROCESS_HELPER_READY_PATH"), 2*time.Second) {
+			os.Exit(4)
+		}
+		if mode == "leader-fail-redirected" {
+			os.Exit(9)
+		}
+		os.Exit(0)
+	case "descendant-after-release":
+		if os.Getenv("SUBPROCESS_HELPER_IGNORE_TERM") == "1" {
+			signal.Ignore(syscall.SIGTERM)
+		}
+		if err := os.WriteFile(os.Getenv("SUBPROCESS_HELPER_READY_PATH"), []byte("ready"), 0o600); err != nil {
+			os.Exit(4)
+		}
+		deadline := time.Now().Add(10 * time.Second)
+		for time.Now().Before(deadline) {
+			if _, err := os.Stat(os.Getenv("SUBPROCESS_HELPER_RELEASE_PATH")); err == nil {
+				_ = os.WriteFile(os.Getenv("SUBPROCESS_HELPER_SENTINEL_PATH"), []byte("survived"), 0o600)
+				os.Exit(0)
+			} else if !errors.Is(err, os.ErrNotExist) {
+				os.Exit(5)
+			}
+			time.Sleep(10 * time.Millisecond)
+		}
+		os.Exit(0)
 	case "descendant":
 		time.Sleep(500 * time.Millisecond)
 		_ = os.WriteFile(os.Getenv("SUBPROCESS_HELPER_SENTINEL_PATH"), []byte("survived"), 0o600)
@@ -770,3 +807,16 @@ func waitForHelperFile(t *testing.T, path string) {
 	}
 	t.Fatalf("helper file %q was not created", path)
 }
+
+func helperFileAppeared(path string, timeout time.Duration) bool {
+	deadline := time.Now().Add(timeout)
+	for time.Now().Before(deadline) {
+		if _, err := os.Stat(path); err == nil {
+			return true
+		} else if !errors.Is(err, os.ErrNotExist) {
+			return false
+		}
+		time.Sleep(10 * time.Millisecond)
+	}
+	return false
+}