- gh-20 @nulian
"* * 31 11 *"aka "every 31th of November"
The easy way out would be to run #next_time right after instantiation to determine if the cron is valid. But that has a cost (around 0.2s for those worst cases).
#parse_and_validate('* * 31 11 *') maybe?
Another way would be to have some smart validation. But that's almost like duplicating #next_time.
Note that https://crontab.guru does consider "* * 31 11 *". Crond probably never schedules it, silently. (Up to the tools that use fugit then).