(Bash) 関数内で配列内容を編集する

配列内のすべての項目を20文字まで空白で埋めようとしていますが、ループが機能しないようです。配列項目を正しく増やすようですが、項目を変更しません。ここで私はどこで間違っていますか？

#!/bin/bash

testArray=( "bish" "bash" "bosh")

padLine () {
array=( "${@}" )
testLength=20
counter=0

##loop begins here##
for i in "${array[@]}";
do
size=${#array[$counter]}
testLength=20

#echo ""
#echo "size: " $size
#echo "Tlength: " $testLength
#echo "count: " ${array[$counter]}
#echo ""

if [ $size -lt $testLength ]
then 
    offset=$( expr $testLength - $size )

    #echo "Offset: " $offset

    case $offset in
        0)
            l0=""
            ;;
        1)
            l1=" "
            array[$counter]=${array[$counter]/%/$l1};;
        2)
            l2="  "
            array[$counter]="${array[$counter]/%/$l2}";;
        3)
            l3="   "
            array[$counter]=${array[$counter]/%/$l3};;
        4)
            l4="    "
            array[$counter]="${array[$counter]/%/$l4}";;
        5)
            l5="     "
            array[$counter]="${array[$counter]/%/$l5}";;
        6)
            l6="      "
            array[$counter]=${array[$counter]/%/$l6};;
        7)
            l7="       "
            array[$counter]=${array[$counter]/%/$l7};;
        8)
            l8="        "
            array[$counter]=${array[$counter]/%/$l8};;
        9)
            l9="         "
            array[$counter]=${array[$counter]/%/$l9};;
        10)
            l10="          "
            array[$counter]=${array[$counter]/%/$l10};;
        11)
            l11="           "
            array[$counter]=${array[$counter]/%/$l11};;
        12)
            l12="            "
            array[$counter]=${array[$counter]/%/$l12};;
        13)
            l13="             "
            array[$counter]=${array[$counter]/%/$l13};;
        14)
            l14="              "
            array[$counter]=${array[$counter]/%/$l14};;
        15)
            l15="               "
            array[$counter]=${array[$counter]/%/$l15};;
        16)
            l16="                "
            array[$counter]=${array[$counter]/%/$l16};;
        17)
            l17="                 "
            array[$counter]=${array[$counter]/%/$l17};;
        18)
            l18="                  "
            array[$counter]=${array[$counter]/%/$l18};;
        19)
            l19="                   "
            array[$counter]=${array[$counter]/%/$l19};;

        *)
    esac
fi
counter=$( expr $counter + 1 )  
done
}

padLine "${testArray[@]}"


echo -e "${testArray[0]}" 
echo -e "${testArray[1]}"
echo -e "${testArray[2]}"

予想出力：

bish                #lines end here, padded to 20 chars
bash                #                
bosh                #

実際の出力：

bish# no padding
bash
bosh