add readOnly on failover opts (#3281)

* add readOnly on failover opts

add failover that if is True it connects to slaves

* add test

* add test for slave connect

* fix test

* fix tests

* skip Flaky

* add more tests on slave

* add test

* delete file

* Update universal_test.go

enable previously skipped test.

* rm skip from sentinels

* rm tmp files

* Update universal_test.go

don't run sentinel test in RE

* Update universal_test.go

---------

Co-authored-by: Nedyalko Dyakov <nedyalko.dyakov@gmail.com>

universal.go

@@ -163,6 +163,8 @@ func (o *UniversalOptions) Failover() *FailoverOptions {
 
 		TLSConfig: o.TLSConfig,
 
+		ReplicaOnly:     o.ReadOnly,
+
 		DisableIndentity: o.DisableIndentity,
 		IdentitySuffix:   o.IdentitySuffix,
 		UnstableResp3:    o.UnstableResp3,

universal_test.go

@@ -60,6 +60,25 @@ var _ = Describe("UniversalClient", func() {
 		Expect(a).ToNot(Panic())
 	})
 
+	It("should connect to failover servers on slaves when readonly Options is ok", Label("NonRedisEnterprise"), func() {
+		client = redis.NewUniversalClient(&redis.UniversalOptions{
+			MasterName: sentinelName,
+			Addrs:      sentinelAddrs,
+			ReadOnly:   true,
+		})
+		Expect(client.Ping(ctx).Err()).NotTo(HaveOccurred())
+
+		roleCmd := client.Do(ctx, "ROLE")
+		role, err := roleCmd.Result()
+		Expect(err).NotTo(HaveOccurred())
+
+		roleSlice, ok := role.([]interface{})
+		Expect(ok).To(BeTrue())
+		Expect(roleSlice[0]).To(Equal("slave"))
+
+		err = client.Set(ctx, "somekey", "somevalue", 0).Err()
+		Expect(err).To(HaveOccurred())
+	})
 	It("should connect to clusters if IsClusterMode is set even if only a single address is provided", Label("NonRedisEnterprise"), func() {
 		client = redis.NewUniversalClient(&redis.UniversalOptions{
 			Addrs:         []string{cluster.addrs()[0]},
@@ -77,3 +96,4 @@ var _ = Describe("UniversalClient", func() {
 		Expect(client.ClusterSlots(ctx).Val()).To(HaveLen(3))
 	})
 })
+