WP-CLI
Cron jobs can be tested using WP-CLI. It offers commands like wp cron event list and wp cron event run {job name}. Check the documentation for more details.
WP-Cron Management Plugins
_get_cron_array()
The _get_cron_array() function returns an array of all currently scheduled cron events. Use this function if you need to inspect the raw list of events.
wp_get_schedules()
The wp_get_schedules() function returns an array of available event recurrence schedules. Use this function if you need to inspect the raw list of available schedules.