From 0afd81cc40acded69a404428d413d7bb45de80df Mon Sep 17 00:00:00 2001
From: NguyenNguyen <nguyenbk92@gmail.com>
Date: Thu, 11 Apr 2019 14:10:27 +0700
Subject: [PATCH] Check empty list

---
 consensus/posv/posv.go      | 3 +++
 consensus/posv/posv_test.go | 9 +++++++++
 2 files changed, 12 insertions(+)

diff --git a/consensus/posv/posv.go b/consensus/posv/posv.go
index 24cb26d059..6804f348d5 100644
--- a/consensus/posv/posv.go
+++ b/consensus/posv/posv.go
@@ -447,6 +447,9 @@ func (c *Posv) verifyCascadingFields(chain consensus.ChainReader, header *types.
 // compare 2 signers lists
 // return true if they are same elements, otherwise return false
 func compareSignersLists(list1 []common.Address, list2 []common.Address) bool {
+	if len(list1) == 0 && len(list2) == 0 {
+		return true
+	}
 	sort.Slice(list1, func(i, j int) bool {
 		return list1[i].String() <= list1[j].String()
 	})
diff --git a/consensus/posv/posv_test.go b/consensus/posv/posv_test.go
index 1ccf9f7860..56c94e7521 100644
--- a/consensus/posv/posv_test.go
+++ b/consensus/posv/posv_test.go
@@ -72,4 +72,13 @@ func TestCompareSignersLists(t *testing.T) {
 	if compareSignersLists(list1, list3) {
 		t.Error("list1 and list3 should not be same", "list1", list1, "list3", list3)
 	}
+	if !compareSignersLists([]common.Address{}, []common.Address{}) {
+		t.Error("Failed with empty list")
+	}
+	if !compareSignersLists([]common.Address{common.StringToAddress("cccccccccccccccccccccccccccccccccccccccc")}, []common.Address{common.StringToAddress("cccccccccccccccccccccccccccccccccccccccc")}) {
+		t.Error("Failed with list has only one signer")
+	}
+	if compareSignersLists([]common.Address{common.StringToAddress("aaaaaaaaaaaaaaaa")}, []common.Address{common.StringToAddress("cccccccccccccccccccccccccccccccccccccccc")}) {
+		t.Error("Failed with list has only one signer")
+	}
 }