How to see the data without sending a test Slack

plugin.php

//Rock the Slackbot Customizations
add_filter( 'rock_the_slackbot_notification', 'edd_sales_slack_notification', 10, 3 );
function edd_sales_slack_notification( $notification, $notification_event, $event_args ) {
	
	echo "<pre>";
	print_r( $notification );
	echo "</pre>";
	exit;

	// Change the pieces
	$notification[ 'payload' ][ 'text' ] = 'Test Message';

	// Return the notification
	return $notification;
}

This is great. Just what I needed. Thanks!