failures=
failure() {
	echo "Error at line $1" >&2
	failures=x$failures
}

T=$(mktemp -d ${TMPDIR:-/tmp}/sh-test.XXXXXX) || exit
trap 'rm -rf $T' 0
cd $T || exit 3
unset x
echo 'x=2' >testscript
. -- ./testscript
[ "$x" = 2 ] || failure $LINENO
cd / || exit 3
x=1
PATH=$T:$PATH . -- testscript
[ "$x" = 2 ] || failure $LINENO

test -z "$failures"