1 files changed, 51 insertions, 0 deletions
diff --git a/tvix/nar-bridge/pkg/writer/writer_pick_next_node_test.go b/tvix/nar-bridge/pkg/writer/writer_pick_next_node_test.go
new file mode 100644
index 000000000000..3601e9fb5296
--- /dev/null
+++ b/tvix/nar-bridge/pkg/writer/writer_pick_next_node_test.go
@@ -0,0 +1,51 @@
+package writer
+
+import (
+	"testing"
+
+	storev1pb "code.tvl.fyi/tvix/store/protos"
+	"github.com/google/go-cmp/cmp"
+	"github.com/stretchr/testify/require"
+	"google.golang.org/protobuf/testing/protocmp"
+)
+
+func requireProtoEq(t *testing.T, expected interface{}, actual interface{}) {
+	if diff := cmp.Diff(expected, actual, protocmp.Transform()); diff != "" {
+		t.Errorf("unexpected difference:\n%v", diff)
+	}
+}
+
+func TestPopNextNode(t *testing.T) {
+	t.Run("empty directory", func(t *testing.T) {
+		d := &storev1pb.Directory{
+			Directories: []*storev1pb.DirectoryNode{},
+			Files:       []*storev1pb.FileNode{},
+			Symlinks:    []*storev1pb.SymlinkNode{},
+		}
+
+		n := drainNextNode(d)
+		require.Equal(t, nil, n)
+	})
+	t.Run("only directories", func(t *testing.T) {
+		ds := &storev1pb.Directory{
+			Directories: []*storev1pb.DirectoryNode{{
+				Name:   []byte("a"),
+				Digest: []byte{},
+				Size:   0,
+			}, {
+				Name:   []byte("b"),
+				Digest: []byte{},
+				Size:   0,
+			}},
+			Files:    []*storev1pb.FileNode{},
+			Symlinks: []*storev1pb.SymlinkNode{},
+		}
+
+		n := drainNextNode(ds)
+		requireProtoEq(t, &storev1pb.DirectoryNode{
+			Name:   []byte("a"),
+			Digest: []byte{},
+			Size:   0,
+		}, n)
+	})
+}