add manual test case of subscription with no result file defined

tests/pytest/tools/taosdemoAllTest/sub_no_result.json

+{
+    "filetype": "subscribe",
+    "cfgdir": "/etc/taos",
+    "host": "127.0.0.1",
+    "port": 6030,
+    "user": "root",
+    "password": "taosdata",
+    "databases": "db",
+    "confirm_parameter_prompt": "no",
+    "specified_table_query":
+        {
+         "concurrent":1,
+         "mode":"sync",
+         "interval": 0,
+         "restart":"yes",
+         "keepProgress":"no",
+         "endAfterConsume": 1100000,
+         "sqls": [
+          {
+            "sql": "select * from st;",
+            "result": ""
+          }]
+        }
+  }
+  
\ No newline at end of file

tests/pytest/tools/taosdemoAllTest/subscribeNoResult.py

+###################################################################
+#           Copyright (c) 2016 by TAOS Technologies, Inc.
+#                     All rights reserved.
+#
+#  This file is proprietary and confidential to TAOS Technologies.
+#  No part of this file may be reproduced, stored, transmitted,
+#  disclosed or used in any form or by any means other than as
+#  expressly provided by the written permission from Jianhui Tao
+#
+###################################################################
+
+# -*- coding: utf-8 -*-
+
+import sys
+import os
+import time
+from util.log import *
+from util.cases import *
+from util.sql import *
+from util.dnodes import *
+import _thread
+
+class TDTestCase:
+    def init(self, conn, logSql):
+        tdLog.debug("start to execute %s" % __file__)
+        tdSql.init(conn.cursor(), logSql)
+        
+        self.ts = 1601481600000
+        self.numberOfRecords = 1100000
+    
+    def execCmdAndGetOutput(self, cmd):  
+        r = os.popen(cmd)  
+        text = r.read()  
+        r.close()  
+        return text
+
+    def getBuildPath(self):
+        selfPath = os.path.dirname(os.path.realpath(__file__))
+
+        if ("community" in selfPath):
+            projPath = selfPath[:selfPath.find("community")]
+        else:
+            projPath = selfPath[:selfPath.find("tests")]
+
+        for root, dirs, files in os.walk(projPath):
+            if ("taosd" in files):
+                rootRealPath = os.path.dirname(os.path.realpath(root))
+                if ("packaging" not in rootRealPath):
+                    buildPath = root[:len(root)-len("/build/bin")]
+                    break
+        return buildPath
+
+    def run(self):
+        buildPath = self.getBuildPath()
+        tdSql.prepare()
+        tdSql.execute("create table st(ts timestamp, c1 timestamp, c2 int, c3 bigint, c4 float, c5 double, c6 binary(8), c7 smallint, c8 tinyint, c9 bool, c10 nchar(8)) tags(t1 int)")
+        tdSql.execute("create table t1 using st tags(0)")
+        currts = self.ts
+        finish = 0
+        while(finish < self.numberOfRecords):
+            sql = "insert into t1 values"
+            for i in range(finish, self.numberOfRecords):
+                sql += "(%d, 1019774612, 29931, 1442173978, 165092.468750, 1128.643179, 'MOCq1pTu', 18405, 82, 0, 'g0A6S0Fu')" % (currts + i)
+                finish = i + 1
+                if (1048576 - len(sql)) < 16384:
+                 break
+            tdSql.execute(sql)
+        
+        binPath = buildPath+ "/build/bin/"
+
+        os.system("%staosdemo -f tools/taosdemoAllTest/sub_no_result.json -g 2>&1 | tee sub_no_result.log" % binPath)
+        test_line = int(self.execCmdAndGetOutput("cat sub_no_result.log | wc -l"))
+        if(test_line < 1100024):
+            tdLog.exit("failed test subscribeNoResult: %d != expected(1100024)" % test_line)
+
+    def stop(self):
+        tdSql.close()
+        tdLog.success("%s successfully executed" % __file__)
+
+
+tdCases.addWindows(__file__, TDTestCase())
+tdCases.addLinux(__file__, TDTestCase())
\ No newline at end of file