diff --git a/dhl.sh b/dhl.sh
index 08e79f7..773afa1 100755
--- a/dhl.sh
+++ b/dhl.sh
@@ -1,5 +1,10 @@
 #!/usr/bin/env sh
 dependencies="sed test cp libreoffice expr cut"
+
+# target filename
+tn1="dhl-cp1252-n.csv"
+tn2="dhl-cp1252-rn.csv"
+
 assert_tools () {
 	while test $# -gt 0; do
 		which $1  >/dev/null 2>/dev/null || {
@@ -17,11 +22,28 @@ testcmp () {
 		echo "arguments missing."; exit 1
 	fi
 	# whitelisted functions
-	case $2 in 
+	case $2 in
+	# 2 arg functions where file exists
+	convnl)
+		expect="$1"
+		fn="$2"
+		shift 2
+		if test -e "$expect" ; then
+			echo "not testing as result $expect already exists."
+		else
+			result=$("$fn" "$1" "$2")
+			if test -e $expect ; then
+				echo "passed $fn for: $1 $2."
+			else
+				echo "failed $fn for: $1 $2."
+			fi
+		fi
+	;;
 	# 2 arg functions
 	chklength|stringcrop)
-		expect="$1"; shift
-		fn="$1"; shift
+		expect="$1"
+		fn="$2"
+		shift 2
 		while test "$#" -ge "2"; do
 			result=$("$fn" "$1" "$2")
 			if test "$result" = "$expect" ; then
@@ -34,8 +56,9 @@ testcmp () {
 	;;
 	# 1 arg functions
 	iso3countrycode)
-		expect="$1"; shift
-		fn="$1"; shift
+		expect="$1"
+		fn="$2"
+		shift 2
 		for a in "$@"; do 
 			result=$("$fn" "$a")
 			if test "$result" = "$expect" ; then
@@ -61,7 +84,6 @@ testchklength () {
 	testcmp "true" "chklength" "3" "123"
 	testcmp "3" "chklength" "2" "1-2"
 }
-testchklength
 
 stringcrop () {
 	echo "$1" | cut -c1-"$2"
@@ -70,7 +92,6 @@ stringcrop () {
 teststringcrop () {
 	testcmp "string" "stringcrop" "string too long" "6"
 }
-teststringcrop
 
 # convert country to countrycode as in ISO3
 iso3countrycode () {
@@ -103,17 +124,38 @@ testiso3 () {
 	testcmp "CHE" "iso3countrycode" "Schweiz"
 	testcmp "" "iso3countrycode" "Simbabwe" # should fail
 }
-testiso3
-exit 0;
 
-# target filename
-tn="dhl-cp1252.csv"
+# replace newline 0a with 0d 0a for dos version
+# test with: echo | sed 's/$'"/`echo \\\r`/" | hexdump
+convnl () {
+	if="$1"
+	of="$2"
+	shift 2
+	expect="0a0d" # hexdump does reverse the byte order
+	result=$(echo | sed 's/$'"/`echo \\\r`/" | hexdump |head -1|cut -d" " -f2)
+	if test $expect = $result ; then
+		sed -e 's/$'"/`echo \\\r`/" "$if" > "$of"
+	fi
+}
+testconvnl () {
+	testcmp "$tn2" "convnl" "$tn1" "$tn2" && rm "$tn2"
+}
+
+runtests () {
+	testchklength
+	teststringcrop
+	testiso3
+	testconvnl
+}
+runtests
 
 # todo: download file (its UTF-8 encoded)
 
 fn="dhl.csv"
 # backup
-cp -f "${fn}" "${fn}.bak"
+cp -f "$fn" "${fn}.bak"
+
+exit 0;
 
 # replace special spaces and hyphens
 sed -i -e 's/[\u00A0\u202F[:space:]]+/ /g' -e 's/[\u2010\u2011\u2012\u2013\u002D]+/-/g' -e 's/[\u00AD\uFEFF]+//g' "$fn"