# $FreeBSD: releng/12.1/bin/sh/tests/expansion/cmdsubst18.0 314637 2017-03-03 22:46:20Z jilles $

x=X
unset n
r=${x+$(echo a)}${x-$(echo b)}${n+$(echo c)}${n-$(echo d)}$(echo e)
[ "$r" = aXde ]