gistfile1.php

<?php

/**
 * Autocomplete orders with virtual products (WC 2.2+)
 *
 * @see https://metorik.com/blog/autocomplete-all-the-orders-in-woocommerce
 */
function bryce_autocomplete_virtual_orders( $order_status, $order_id ) {

	$order = wc_get_order( $order_id );
	if ( 'processing' == $order_status && ( 'on-hold' == $order->status || 'pending' == $order->status || 'failed' == $order->status ) ) {

		$virtual_order = '';
		if ( count( $order->get_items() ) > 0 ) {
			foreach ( $order->get_items() as $item ) {
				if ( 'line_item' == $item['type'] ) {
					$_product = $order->get_product_from_item( $item );
					if ( ! $_product->is_virtual() ) {
						$virtual_order = false;
						break;
					} else {
						$virtual_order = true;
					}
				}
			}
		}
		if ( $virtual_order ) {
			return 'completed';
		}
	}
	return $order_status;
}
add_filter( 'woocommerce_thankyou', 'bryce_autocomplete_virtual_orders', 10, 2 );