clientv3: pass "grpc.WithBlock" on "TestDialTimeout"

Otherwise, grpc.DialContext would just return before
connection is up.

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

clientv3/client_test.go

@@ -23,6 +23,8 @@ import (
 
 	"github.com/coreos/etcd/etcdserver/api/v3rpc/rpctypes"
 	"github.com/coreos/etcd/pkg/testutil"
+
+	"google.golang.org/grpc"
 )
 
 func TestDialCancel(t *testing.T) {
@@ -80,14 +82,17 @@ func TestDialCancel(t *testing.T) {
 func TestDialTimeout(t *testing.T) {
 	defer testutil.AfterTest(t)
 
+	// grpc.WithBlock to block until connection up or timeout
 	testCfgs := []Config{
 		{
 			Endpoints:   []string{"http://254.0.0.1:12345"},
 			DialTimeout: 2 * time.Second,
+			DialOptions: []grpc.DialOption{grpc.WithBlock()},
 		},
 		{
 			Endpoints:   []string{"http://254.0.0.1:12345"},
 			DialTimeout: time.Second,
+			DialOptions: []grpc.DialOption{grpc.WithBlock()},
 			Username:    "abc",
 			Password:    "def",
 		},