fish-shell/tests/test_cmdsub.in

# This tests various corner cases involving command substitution. Most
# importantly the limits on the amount of data we'll substitute.

set FISH_READ_BYTE_LIMIT 512

function subme
    set -l x (string repeat -n $argv x)
    echo $x
end

logmsg Command sub just under the limit should succeed
set a (subme 511)
set --show a

logmsg Command sub at the limit should fail
set b (string repeat -n 512 x)
set saved_status $status
test $saved_status -eq 122
or echo expected status 122, saw $saved_status >&2
set --show b

logmsg Command sub over the limit should fail
set c (subme 513)
set --show c

logmsg Make sure output from builtins outside of command substitution is not affected
string repeat --max 513 a

logmsg Same builtin in a command substitution is affected
echo this will fail (string repeat --max 513 b) to output anything
set saved_status $status
test $saved_status -eq 122
or echo expected status 122, saw $saved_status >&2