*: make TestEtcdScaleInAndOut stable (#8067)

close #6892

Signed-off-by: Ryan Leung <[email protected]>

Co-authored-by: ti-chi-bot[bot] <108142056+ti-chi-bot[bot]@users.noreply.github.com>

pkg/utils/etcdutil/testutil.go

@@ -122,18 +122,27 @@ func MustAddEtcdMember(t *testing.T, cfg1 *embed.Config, client *clientv3.Client
 
 func checkMembers(re *require.Assertions, client *clientv3.Client, etcds []*embed.Etcd) {
 	// Check the client can get the new member.
-	listResp, err := ListEtcdMembers(client.Ctx(), client)
-	re.NoError(err)
-	re.Len(listResp.Members, len(etcds))
-	inList := func(m *etcdserverpb.Member) bool {
-		for _, etcd := range etcds {
-			if m.ID == uint64(etcd.Server.ID()) {
-				return true
+	testutil.Eventually(re, func() bool {
+		listResp, err := ListEtcdMembers(client.Ctx(), client)
+		if err != nil {
+			return false
+		}
+		if len(etcds) != len(listResp.Members) {
+			return false
+		}
+		inList := func(m *etcdserverpb.Member) bool {
+			for _, etcd := range etcds {
+				if m.ID == uint64(etcd.Server.ID()) {
+					return true
+				}
 			}
+			return false
 		}
-		return false
-	}
-	for _, m := range listResp.Members {
-		re.True(inList(m))
-	}
+		for _, m := range listResp.Members {
+			if !inList(m) {
+				return false
+			}
+		}
+		return true
+	})
 }