CompTIA Linux+ XK0-006 (V8) Practice Question

You are writing a portable shell script that must run under /bin/sh on several Linux servers. The script counts the number of available security updates and stores the result in a variable named updates. If the count is not equal to 0, the script should call a notify_updates function. A fragment of the script looks like:

updates=$(dnf check-update --security 2>/dev/null | grep -vc '^$')
if [ _____ ]; then   # TODO: insert test expression
    notify_updates "$updates"
fi

Which test expression should replace the blank so the condition is satisfied only when updates is numerically not equal to 0, using the single-bracket POSIX test ([ ]) builtin?