From 753402c336159ce559ef9ab4e1655337e109ee11 Mon Sep 17 00:00:00 2001
From: Pavel Karpy <carpawell@nspcc.ru>
Date: Tue, 8 Jun 2021 19:37:35 +0300
Subject: [PATCH] [#302] pkg/object: Convert nil `Tombstone` to nil message

Document that `NewTombstoneFromV2` function return
`nil` when called on `nil`. Write corresponding
unit tests.

Signed-off-by: Pavel Karpy <carpawell@nspcc.ru>
---
 pkg/object/splitid_test.go   | 1 +
 pkg/object/tombstone.go      | 2 ++
 pkg/object/tombstone_test.go | 9 +++++++++
 3 files changed, 12 insertions(+)

diff --git a/pkg/object/splitid_test.go b/pkg/object/splitid_test.go
index 8adcc86..04b40f7 100644
--- a/pkg/object/splitid_test.go
+++ b/pkg/object/splitid_test.go
@@ -45,3 +45,4 @@ func TestSplitID(t *testing.T) {
 		})
 	})
 }
+
diff --git a/pkg/object/tombstone.go b/pkg/object/tombstone.go
index 469e684..add7f5d 100644
--- a/pkg/object/tombstone.go
+++ b/pkg/object/tombstone.go
@@ -9,6 +9,8 @@ import (
 type Tombstone tombstone.Tombstone
 
 // NewTombstoneFromV2 wraps v2 Tombstone message to Tombstone.
+//
+// Nil tombstone.Tombstone converts to nil.
 func NewTombstoneFromV2(tV2 *tombstone.Tombstone) *Tombstone {
 	return (*Tombstone)(tV2)
 }
diff --git a/pkg/object/tombstone_test.go b/pkg/object/tombstone_test.go
index 21103ba..f9a0650 100644
--- a/pkg/object/tombstone_test.go
+++ b/pkg/object/tombstone_test.go
@@ -5,6 +5,7 @@ import (
 	"crypto/sha256"
 	"testing"
 
+	"github.com/nspcc-dev/neofs-api-go/v2/tombstone"
 	"github.com/stretchr/testify/require"
 )
 
@@ -63,3 +64,11 @@ func TestTombstoneEncoding(t *testing.T) {
 		require.Equal(t, ts, ts2)
 	})
 }
+
+func TestNewTombstoneFromV2(t *testing.T) {
+	t.Run("from nil", func(t *testing.T) {
+		var x *tombstone.Tombstone
+
+		require.Nil(t, NewTombstoneFromV2(x))
+	})
+}