clientv3/integration: add TestBalancerUnderNetworkPartitionWatch

Signed-off-by: Gyu-Ho Lee <gyuhox@gmail.com>

clientv3/integration/network_partition_test.go

@@ -99,3 +99,69 @@ func testBalancerUnderNetworkPartition(t *testing.T, op func(*clientv3.Client, c
 		t.Errorf("balancer did not switch in time (%v)", err)
 	}
 }
+
+func TestBalancerUnderNetworkPartitionWatchLeader(t *testing.T) {
+	testBalancerUnderNetworkPartitionWatch(t, true)
+}
+
+func TestBalancerUnderNetworkPartitionWatchFollower(t *testing.T) {
+	testBalancerUnderNetworkPartitionWatch(t, false)
+}
+
+// testBalancerUnderNetworkPartitionWatch ensures watch stream
+// to a partitioned node be closed when context requires leader.
+func testBalancerUnderNetworkPartitionWatch(t *testing.T, isolateLeader bool) {
+	defer testutil.AfterTest(t)
+
+	clus := integration.NewClusterV3(t, &integration.ClusterConfig{
+		Size:               3,
+		SkipCreatingClient: true,
+	})
+	defer clus.Terminate(t)
+
+	eps := []string{clus.Members[0].GRPCAddr(), clus.Members[1].GRPCAddr(), clus.Members[2].GRPCAddr()}
+
+	target := clus.WaitLeader(t)
+	if !isolateLeader {
+		target = (target + 1) % 3
+	}
+
+	// pin eps[target]
+	watchCli, err := clientv3.New(clientv3.Config{Endpoints: []string{eps[target]}})
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer watchCli.Close()
+
+	// wait for eps[target] to be pinned
+	waitPinReady(t, watchCli)
+
+	// add all eps to list, so that when the original pined one fails
+	// the client can switch to other available eps
+	watchCli.SetEndpoints(eps...)
+
+	wch := watchCli.Watch(clientv3.WithRequireLeader(context.Background()), "foo", clientv3.WithCreatedNotify())
+	select {
+	case <-wch:
+	case <-time.After(3 * time.Second):
+		t.Fatal("took too long to create watch")
+	}
+
+	// isolate eps[target]
+	clus.Members[target].InjectPartition(t,
+		clus.Members[(target+1)%3],
+		clus.Members[(target+2)%3],
+	)
+
+	select {
+	case ev := <-wch:
+		if len(ev.Events) != 0 {
+			t.Fatal("expected no event")
+		}
+		if err = ev.Err(); err != rpctypes.ErrNoLeader {
+			t.Fatalf("expected %v, got %v", rpctypes.ErrNoLeader, err)
+		}
+	case <-time.After(3 * time.Second): // enough time to detect leader lost
+		t.Fatal("took too long to detect leader lost")
+	}
+}