fix unit test

Author: carter2000

cluster_test.go

@@ -2092,7 +2092,7 @@ func (s *S) TestDoNotFallbackToMonotonic(c *C) {
 
 func (s *S) TestConnectServerFailed(c *C) {
 	dials := int32(0)
-	maxDials := 100
+	maxDials := 50
 	info := &mgo.DialInfo{
 		Addrs: []string{"localhost:40001"},
 		DialServer: func(addr *mgo.ServerAddr) (net.Conn, error) {
@@ -2112,16 +2112,18 @@ func (s *S) TestConnectServerFailed(c *C) {
 
 	errs := make(chan error, 1)
 	var done int32
-	var wg sync.WaitGroup
+	var finished sync.WaitGroup
+	var starting sync.WaitGroup
 	defer func() {
 		atomic.StoreInt32(&done, 1)
-		wg.Wait()
+		finished.Wait()
 	}()
 	for i := 0; i < maxDials; i++ {
-		wg.Add(1)
+		finished.Add(1)
+		starting.Add(1)
 		go func(s0 *mgo.Session) {
-			defer wg.Done()
-			for {
+			defer finished.Done()
+			for i := 0; ; i++ {
 				if atomic.LoadInt32(&done) == 1 {
 					break
 				}
@@ -2139,10 +2141,14 @@ func (s *S) TestConnectServerFailed(c *C) {
 					default:
 					}
 				}
+				if i == 0 {
+					starting.Done()
+				}
 			}
 		}(session)
 		time.Sleep(10 * time.Millisecond)
 	}
+	starting.Wait()
 
 	// no errors expect.
 	var opErr error