Snippet to create scheduled actions with Action Scheduler via $_GET params.

create-test-scheduled-actions.php

<?php
/**
 * Check for $_GET params on admin pages and use them to create corresponding actions.
 *
 * Example URL string to append to any admin page: &as_add_actions=single&hook=my_action&time=1563420973
 */
function as_test_schedule_async_action() {
	if ( ! isset( $_GET['as_add_actions'] ) ) {
		return;
	}
	$action_type = $_GET['as_add_actions'];
	$time = ( isset( $_GET['time'] ) ) ? $_GET['time'] : gmdate( 'U' );
	$hook = ( isset( $_GET['hook'] ) ) ? $_GET['hook'] : sprintf( 'test_%s_action', $action_type );

	switch ( $action_type ) {
		case 'async' :
			for( $i = 1; $i < 10; $i++ ) {
				as_enqueue_async_action( $hook, array( 'timestamp' => time(), 'i' => $i ), 'async' );
			}
			break;
		case 'cron' :
			as_schedule_cron_action( $time, '*/10 * * * *', $hook );
			break;
		case 'recurring' :
			as_schedule_recurring_action( $time, 5 * MINUTE_IN_SECONDS, $hook );
			break;
		case 'single' :
			as_schedule_single_action( $time, $hook );
			break;
	}
}
add_action( 'admin_init', 'as_test_schedule_async_action' );