//go:build integration

package builder

import (
	"context"
	"errors"
	"os"
	"path/filepath"
	"strconv"
	"strings"
	"syscall"
	"testing"
	"time"
)

func TestAKilledBuildEndsItsWholeProcessGroup(t *testing.T) {
	dir := t.TempDir()
	child := filepath.Join(dir, "child")
	ctx, cancel := context.WithCancel(context.Background())
	done := make(chan error, 1)
	began := time.Now()
	go func() {
		// A shell that starts a grandchild and waits on it: killing the shell alone would leave the
		// grandchild running, holding the output open.
		_, err := Command(ctx, dir, "sh", "-c", `sleep 60 & echo $! > child; wait`)
		done <- err
	}()
	var pid int
	for deadline := time.Now().Add(5 * time.Second); time.Now().Before(deadline); time.Sleep(20 * time.Millisecond) {
		if raw, err := os.ReadFile(child); err == nil && strings.TrimSpace(string(raw)) != "" {
			pid, _ = strconv.Atoi(strings.TrimSpace(string(raw)))
			break
		}
	}
	if pid == 0 {
		t.Fatal("the command never started its child")
	}
	cancel()
	select {
	case err := <-done:
		if err == nil {
			t.Fatal("a killed command reported success")
		}
	case <-time.After(KillWait + 5*time.Second):
		t.Fatal("the killed command never returned")
	}
	if took := time.Since(began); took > KillWait {
		t.Errorf("ending the command took %s: the group was not killed, the wait ran out", took)
	}
	for deadline := time.Now().Add(2 * time.Second); time.Now().Before(deadline); time.Sleep(20 * time.Millisecond) {
		if err := syscall.Kill(pid, 0); errors.Is(err, syscall.ESRCH) {
			return
		}
	}
	_ = syscall.Kill(pid, syscall.SIGKILL)
	t.Fatalf("the grandchild %d outlived the kill", pid)
}