test: 补齐短时间可测验收并修复建群下行卡住

test/harness/mqtt.go

@@ -34,7 +34,7 @@ func DialMQTTTCP(addr string, timeout time.Duration) (MQTTClient, error) {
 	if err != nil {
 		return nil, err
 	}
-	_ = conn.SetDeadline(time.Now().Add(timeout))
+	_ = conn.SetDeadline(time.Time{})
 	return &tcpMQTT{conn: conn, r: bufio.NewReader(conn)}, nil
 }
 
@@ -126,6 +126,8 @@ func DialMQTTWebSocket(httpBase string, timeout time.Duration) (MQTTClient, erro
 		_ = raw.Close()
 		return nil, fmt.Errorf("unexpected subprotocol %q", proto)
 	}
+	// 握手完成后清掉超时，否则长会话后续读写会在 dial timeout 到期后全部失败。
+	_ = raw.SetDeadline(time.Time{})
 	return &wsMQTT{conn: raw, r: br}, nil
 }