From 5c012a38729f41c0fed43a2975d789ee75f822bd Mon Sep 17 00:00:00 2001
From: Vladimir Mihailenco <vladimir.webdev@gmail.com>
Date: Thu, 7 Mar 2019 12:19:03 +0200
Subject: [PATCH] Use random node when there are no channels

---
 cluster.go      | 9 ++++++---
 cluster_test.go | 8 ++++++++
 2 files changed, 14 insertions(+), 3 deletions(-)

diff --git a/cluster.go b/cluster.go
index e3a6591..c9f1384 100644
--- a/cluster.go
+++ b/cluster.go
@@ -1537,10 +1537,13 @@ func (c *ClusterClient) pubSub() *PubSub {
 				panic("node != nil")
 			}
 
-			slot := hashtag.Slot(channels[0])
-
 			var err error
-			node, err = c.slotMasterNode(slot)
+			if len(channels) > 0 {
+				slot := hashtag.Slot(channels[0])
+				node, err = c.slotMasterNode(slot)
+			} else {
+				node, err = c.nodes.Random()
+			}
 			if err != nil {
 				return nil, err
 			}
diff --git a/cluster_test.go b/cluster_test.go
index 51633e9..f128a8a 100644
--- a/cluster_test.go
+++ b/cluster_test.go
@@ -512,6 +512,14 @@ var _ = Describe("ClusterClient", func() {
 				return nil
 			}, 30*time.Second).ShouldNot(HaveOccurred())
 		})
+
+		It("supports PubSub.Ping without channels", func() {
+			pubsub := client.Subscribe()
+			defer pubsub.Close()
+
+			err := pubsub.Ping()
+			Expect(err).NotTo(HaveOccurred())
+		})
 	}
 
 	Describe("ClusterClient", func() {