add test case for desc fill

tests/script/tsim/parser/fill.sim

@@ -795,12 +795,34 @@ if $data81 != 4 then
 endi
 
 # desc fill query
+print asc fill query
+sql select _wstart,count(*) from m_fl_tb0 where ts>='2018-9-17 9:0:0' and ts<='2018-9-17 9:11:00' interval(1m) fill(value,10) order by _wstart asc;
+if $rows != 12 then
+  return -1
+endi
+
+if $data00 != @18-09-17 09:00:00.000@ then
+  return -1
+endi
+
+if $data01 != 1 then
+  return -1
+endi
+
 print desc fill query
-sql select count(*) from m_fl_tb0 where ts>='2018-9-17 9:0:0' and ts<='2018-9-17 9:11:00' interval(1m) fill(value,10);
+sql select _wstart,count(*) from m_fl_tb0 where ts>='2018-9-17 9:0:0' and ts<='2018-9-17 9:11:00' interval(1m) fill(value,10) order by _wstart desc;
 if $rows != 12 then
   return -1
 endi
 
+if $data00 != @18-09-17 09:11:00.000@ then
+  return -1
+endi
+
+if $data01 != 10 then
+  return -1
+endi
+
 print =====================> aggregation + arithmetic + fill, need to add cases TODO
 #sql select avg(cpu_taosd) - first(cpu_taosd) from dn1 where ts<'2020-11-13 11:00:00' and ts>'2020-11-13 10:50:00' interval(10s) fill(value, 99)
 #sql select count(*), first(k), avg(k), avg(k)-first(k) from tm0 where ts>'2020-1-1 1:1:1' and ts<'2020-1-1 1:02:59' interval(10s) fill(value, 99);