clientv3/integration: add TestBalancerUnderServerShutdownWatch

Current Watch integration tests haven't covered the balancer
switch behavior under server failures.

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

clientv3/integration/server_shutdown_test.go

@@ -0,0 +1,113 @@
+// Copyright 2017 The etcd Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package integration
+
+import (
+	"bytes"
+	"context"
+	"testing"
+	"time"
+
+	"github.com/coreos/etcd/clientv3"
+	"github.com/coreos/etcd/integration"
+	"github.com/coreos/etcd/pkg/testutil"
+)
+
+// TestBalancerUnderServerShutdownWatch expects that watch client
+// switch its endpoints when the member of the pinned endpoint fails.
+func TestBalancerUnderServerShutdownWatch(t *testing.T) {
+	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()}
+
+	lead := clus.WaitLeader(t)
+
+	// pin eps[lead]
+	watchCli, err := clientv3.New(clientv3.Config{Endpoints: []string{eps[lead]}})
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer watchCli.Close()
+
+	// wait for eps[lead] to be pinned
+	watchCli.Get(context.Background(), "foo")
+
+	// add all eps to list, so that when the original pined one fails
+	// the client can switch to other available eps
+	watchCli.SetEndpoints(eps...)
+
+	key, val := "foo", "bar"
+	wch := watchCli.Watch(context.Background(), key, clientv3.WithCreatedNotify())
+	select {
+	case <-wch:
+	case <-time.After(3 * time.Second):
+		t.Fatal("took too long to create watch")
+	}
+
+	donec := make(chan struct{})
+	go func() {
+		defer close(donec)
+
+		// switch to others when eps[lead] is shut down
+		select {
+		case ev := <-wch:
+			if werr := ev.Err(); werr != nil {
+				t.Fatal(werr)
+			}
+			if len(ev.Events) != 1 {
+				t.Fatalf("expected one event, got %+v", ev)
+			}
+			if !bytes.Equal(ev.Events[0].Kv.Value, []byte(val)) {
+				t.Fatalf("expected %q, got %+v", val, ev.Events[0].Kv)
+			}
+		case <-time.After(7 * time.Second):
+			t.Fatal("took too long to receive events")
+		}
+	}()
+
+	// shut down eps[lead]
+	clus.Members[lead].Terminate(t)
+
+	// writes to eps[lead+1]
+	putCli, err := clientv3.New(clientv3.Config{Endpoints: []string{eps[(lead+1)%3]}})
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer putCli.Close()
+	for {
+		ctx, cancel := context.WithTimeout(context.Background(), 2*time.Second)
+		_, err = putCli.Put(ctx, key, val)
+		cancel()
+		if err == nil {
+			break
+		}
+		if err == context.DeadlineExceeded {
+			continue
+		}
+		t.Fatal(err)
+	}
+
+	select {
+	case <-donec:
+	case <-time.After(5 * time.Second): // enough time for balancer switch
+		t.Fatal("took too long to receive events")
+	}
+}