Close piped processes on cancellation

preparation_test.go

@@ -6,12 +6,58 @@ import (
 	"os"
 	"os/exec"
 	"path/filepath"
+	"strconv"
 	"strings"
 	"testing"
+	"time"
 
 	releasekit "go.maximumdirect.net/releasekit"
 )
 
+func TestPrepareBuildDependenciesCancellationReleasesInheritedOutput(t *testing.T) {
+	directory := t.TempDir()
+	ready := filepath.Join(t.TempDir(), "descendant")
+	gitPath := filepath.Join(t.TempDir(), "git")
+	if err := os.WriteFile(gitPath, []byte("#!/bin/sh\nsleep 60 &\nprintf '%s' \"$!\" > \"$RELEASEKIT_PREPARE_DESCENDANT\"\nwait\n"), 0o700); err != nil {
+		t.Fatal(err)
+	}
+	t.Setenv("PATH", filepath.Dir(gitPath)+string(os.PathListSeparator)+os.Getenv("PATH"))
+	t.Setenv("RELEASEKIT_PREPARE_DESCENDANT", ready)
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+	result := make(chan error, 1)
+	go func() {
+		result <- releasekit.PrepareBuildDependencies(ctx, releasekit.DependencyPreparationRequest{RepositoryDir: directory})
+	}()
+	deadline := time.After(10 * time.Second)
+	var pid int
+	for pid == 0 {
+		if data, err := os.ReadFile(ready); err == nil {
+			pid, _ = strconv.Atoi(string(data))
+		}
+		select {
+		case <-deadline:
+			t.Fatal("preparation descendant did not start")
+		default:
+			time.Sleep(10 * time.Millisecond)
+		}
+	}
+	t.Cleanup(func() {
+		if descendant, err := os.FindProcess(pid); err == nil {
+			_ = descendant.Kill()
+		}
+	})
+	cancel()
+	select {
+	case err := <-result:
+		if !errors.Is(err, context.Canceled) {
+			t.Fatalf("preparation error = %v, want cancellation", err)
+		}
+	case <-time.After(10 * time.Second):
+		t.Fatal("preparation did not return after cancellation")
+	}
+}
+
 func TestPrepareTaggedCheckoutFetchesExpectedCommitAndDetaches(t *testing.T) {
 	repository := newTaggedDeliveryConsumer(t)
 	tagCommit := publishPreparationTag(t, repository)