mkfifo fifo ranges 2>/dev/null
exec 5>fifo
printf a >&5
assert_eq 1.1,1.1 "$(cat ranges)"
printf b >&5
assert_eq 1.2,1.2 "$(cat ranges)"
printf 'c\n' >&5
assert_eq 1.3,1.4 "$(cat ranges)"
printf d >&5
assert_eq 2.1,2.1 "$(cat ranges)"
exec 5>&-