From aeb4ad65967178036430221b185830fccd32360d Mon Sep 17 00:00:00 2001
From: Andrey Meshkov <am@adguard.com>
Date: Mon, 5 Feb 2024 15:40:55 +0300
Subject: [PATCH] fix flapping test

---
 internal/testutil/udpechoserver.go | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/internal/testutil/udpechoserver.go b/internal/testutil/udpechoserver.go
index 9e861b7..8702a47 100644
--- a/internal/testutil/udpechoserver.go
+++ b/internal/testutil/udpechoserver.go
@@ -24,7 +24,7 @@ func (s *UDPEchoServer) ReceivedMsg(num int) (b []byte) {
 	s.mu.Lock()
 	defer s.mu.Unlock()
 
-	if len(s.received) < num {
+	if len(s.received) <= num {
 		return nil
 	}
 
@@ -96,10 +96,11 @@ func (s *UDPEchoServer) serveConn(conn net.Conn) {
 
 		msg := make([]byte, n)
 		copy(msg, buf[:n])
-		_, _ = conn.Write(msg)
 
 		s.mu.Lock()
 		s.received = append(s.received, msg)
 		s.mu.Unlock()
+
+		_, _ = conn.Write(msg)
 	}
 }