Bash: read csv file

Here is the script to read csv file in shell script.

#!/bin/bash
FILENAME=test.csv
OLDSEP=$IFS
IFS=,

[ ! -f $FILENAME ] && { echo "File not found : $FILENAME"; exit 99; }

while read field1 field2 field3 field4
do
    echo "$field1 : $field2 : $field3 : $field4"
done < $FILENAME

IFS=$OLDSEP