an unexpected time unit for elapsed function about keyword now

tests/system-test/2-query/9-others/TD-12388.py

+###################################################################
+#           Copyright (c) 2020 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 -*-
+
+from posixpath import split
+import sys
+import os 
+
+from util.log import *
+from util.cases import *
+from util.sql import *
+from util.dnodes import *
+
+class TDTestCase:
+    def init(self, conn, logSql):
+        tdLog.debug("start to execute %s" % __file__)
+        tdSql.init(conn.cursor(), logSql)
+        
+        self.ts = 1420041600000 # 2015-01-01 00:00:00  this is begin time for first record
+        self.num = 10
+
+    def caseDescription(self):
+
+        '''
+        case1 <authors>: wenzhouwww[TD-12388] : 
+            this test case is an test case for unit time params about elapsed function. 
+
+        ''' 
+        return 
+
+   
+    def run(self):
+        tdSql.prepare()
+        tdSql.execute("create database if not exists testdb keep 36500;")
+        tdSql.execute("use testdb;")
+        tdSql.execute("create stable st (ts timestamp , id int , value double) tags(hostname binary(10) ,ind int);")
+        for i in range(self.num):
+            tdSql.execute("insert into sub_%s using st tags('host_%s' , %d) values (%d , %d , %f );"%(str(i),str(i),i*10,self.ts+10000*i,i*2,i+10.00))
+
+        tdSql.error("select elapsed(ts,now+1d-3m) from st group by tbname;")
+        tdSql.error("select elapsed(ts,now) from st group by tbname;")
+        tdSql.error("select elapsed(ts,now*10) from st group by tbname;")
+        tdSql.error("select elapsed(ts,now*2s) from st group by tbname;")
+        tdSql.error("select elapsed(ts,now*2s) from sub_1;")
+       
+
+    def stop(self):
+        tdSql.close()
+        tdLog.success("%s successfully executed" % __file__)
+
+tdCases.addWindows(__file__, TDTestCase())
+tdCases.addLinux(__file__, TDTestCase())
+
+