better quoting in scrollup testing shell script

up.sh

@@ -4,12 +4,12 @@ set -eu
 export POSIXLY_CORRECT=1
 
 i=1
-while test $i -lt 50; do
-	echo $i
+while test "$i" -lt 50; do
+	echo "$i"
 	i=$((i + 1))
 done > tmp.log
 
-(sleep 1; printf "\033[5;2~"; sleep 1; ) \
+(sleep 1; printf '\033[5;2~'; sleep 1; ) \
 	| ./ptty ./scroll tail -fn 50 tmp.log > out.log
 
 cmp out.log up.log