w='@ @'
check() {
	[ "$v" = "$w" ] || echo "Expected $w got $v"
}

export v=$w
check

HOME=/known/value
check() {
	[ "$v" = ~ ] || echo "Expected $HOME got $v"
}

export v=~
check

check() {
	[ "$v" = "x:$HOME" ] || echo "Expected x:$HOME got $v"
}

export v=x:~
check