unset LC_ALL
LC_CTYPE=en_US.UTF-8
export LC_CTYPE

c1=e
# a umlaut
c2=$(printf '\303\244')
# euro sign
c3=$(printf '\342\202\254')
# some sort of 't' outside BMP
c4=$(printf '\360\235\225\245')

ok=0
case $c1$c2$c3$c4 in
*) ok=1 ;;
esac
if [ $ok = 0 ]; then
	echo wrong at $LINENO
	exit 3
fi

case $c1$c2$c3$c4 in
$c1$c2$c3$c4) ;;
*) echo wrong at $LINENO ;;
esac

case $c1$c2$c3$c4 in
"$c1$c2$c3$c4") ;;
*) echo wrong at $LINENO ;;
esac

case $c1$c2$c3$c4 in
????) ;;
*) echo wrong at $LINENO ;;
esac

case $c1.$c2.$c3.$c4 in
?.?.?.?) ;;
*) echo wrong at $LINENO ;;
esac

case $c1$c2$c3$c4 in
[!a][!b][!c][!d]) ;;
*) echo wrong at $LINENO ;;
esac

case $c1$c2$c3$c4 in
[$c1][$c2][$c3][$c4]) ;;
*) echo wrong at $LINENO ;;
esac

case $c1$c2$c3$c4 in
["$c1"]["$c2"]["$c3"]["$c4"]) ;;
*) echo wrong at $LINENO ;;
esac