From 5473b4ef956c7df25827649afaa8d643dfd8bf88 Mon Sep 17 00:00:00 2001
From: Leonard Lyubich <leonard@nspcc.ru>
Date: Fri, 11 Sep 2020 18:18:02 +0300
Subject: [PATCH] [#140] sdk: Implement checksum comparison function

Signed-off-by: Leonard Lyubich <leonard@nspcc.ru>
---
 pkg/checksum.go      |  5 +++++
 pkg/checksum_test.go | 20 ++++++++++++++++++++
 2 files changed, 25 insertions(+)

diff --git a/pkg/checksum.go b/pkg/checksum.go
index 4fa84cd..2a93b39 100644
--- a/pkg/checksum.go
+++ b/pkg/checksum.go
@@ -1,6 +1,7 @@
 package pkg
 
 import (
+	"bytes"
 	"crypto/sha256"
 
 	"github.com/nspcc-dev/neofs-api-go/v2/refs"
@@ -72,3 +73,7 @@ func (c *Checksum) SetTillichZemor(v [64]byte) {
 func (c *Checksum) ToV2() *refs.Checksum {
 	return (*refs.Checksum)(c)
 }
+
+func EqualChecksums(cs1, cs2 *Checksum) bool {
+	return cs1.GetType() == cs2.GetType() && bytes.Equal(cs1.GetSum(), cs2.GetSum())
+}
diff --git a/pkg/checksum_test.go b/pkg/checksum_test.go
index e0da6ef..906f68b 100644
--- a/pkg/checksum_test.go
+++ b/pkg/checksum_test.go
@@ -38,3 +38,23 @@ func TestChecksum(t *testing.T) {
 	require.Equal(t, refs.TillichZemor, cV2.GetType())
 	require.Equal(t, cTZ[:], cV2.GetSum())
 }
+
+func TestEqualChecksums(t *testing.T) {
+	require.True(t, EqualChecksums(nil, nil))
+
+	csSHA := [sha256.Size]byte{}
+	_, _ = rand.Read(csSHA[:])
+
+	cs1 := NewChecksum()
+	cs1.SetSHA256(csSHA)
+
+	cs2 := NewChecksum()
+	cs2.SetSHA256(csSHA)
+
+	require.True(t, EqualChecksums(cs1, cs2))
+
+	csSHA[0]++
+	cs2.SetSHA256(csSHA)
+
+	require.False(t, EqualChecksums(cs1, cs2))
+}