testgit: Add pack object reader and many object maker

1 files changed, 94 insertions, 0 deletions

diff --git a/internal/testgit/repo_pack_objects_reader.go b/internal/testgit/repo_pack_objects_reader.go
new file mode 100644
index 00000000..dc997514
--- /dev/null
+++ b/internal/testgit/repo_pack_objects_reader.go
@@ -0,0 +1,94 @@
+package testgit
+
+import (
+	"fmt"
+	"io"
+	"os/exec"
+	"strings"
+	"sync"
+	"testing"
+)
+
+// packObjectsReadCloser wraps a pipe reader and process wait fn.
+type packObjectsReadCloser struct {
+	reader io.ReadCloser
+	wait   func() error
+	once   sync.Once
+}
+
+// Read proxies reads to the wrapped reader.
+func (reader *packObjectsReadCloser) Read(dst []byte) (int, error) {
+	return reader.reader.Read(dst)
+}
+
+// Close closes the stream and waits for the underlying process.
+func (reader *packObjectsReadCloser) Close() error {
+	var out error
+
+	reader.once.Do(func() {
+		errClose := reader.reader.Close()
+		errWait := reader.wait()
+
+		if errClose != nil {
+			out = errClose
+
+			return
+		}
+
+		out = errWait
+	})
+
+	return out
+}
+
+// PackObjectsReader streams `git pack-objects --stdout --revs` output.
+func (testRepo *TestRepo) PackObjectsReader(tb testing.TB, revs []string, thin bool) io.ReadCloser {
+	tb.Helper()
+
+	args := []string{"pack-objects", "--stdout", "--revs"}
+	if thin {
+		args = append(args, "--thin")
+	}
+
+	//nolint:noctx
+	cmd := exec.Command("git", args...) //#nosec G204
+	cmd.Dir = testRepo.dir
+	cmd.Env = testRepo.env
+	cmd.Stdin = strings.NewReader(strings.Join(revs, "\n") + "\n")
+
+	pr, pw := io.Pipe()
+	cmd.Stdout = pw
+	stderr := &strings.Builder{}
+	cmd.Stderr = stderr
+
+	waitDone := make(chan error, 1)
+
+	go func() {
+		err := cmd.Start()
+		if err != nil {
+			_ = pw.CloseWithError(fmt.Errorf("git %v start failed: %w", args, err))
+
+			waitDone <- nil
+
+			return
+		}
+
+		err = cmd.Wait()
+		if err != nil {
+			_ = pw.CloseWithError(fmt.Errorf("git %v failed: %w\n%s", args, err, stderr.String()))
+		} else {
+			_ = pw.Close()
+		}
+
+		waitDone <- nil
+	}()
+
+	return &packObjectsReadCloser{
+		reader: pr,
+		wait: func() error {
+			<-waitDone
+
+			return nil
+		},
+	}
+}