cx-newsletter/views/7-sending_test.php

<?php

namespace cx_newsletter;
use \add_submenu_page;

class sending_test_view
extends view
implements view_interface {
    public function connect() : void {
        add_submenu_page(
            'cx_newsletter',
            __('Sending test', 'cx_newsletter'),
            __('Sending test', 'cx_newsletter'),
            'customize',
            'cx_newsletter_sending_test',
            [$this, 'action']
        );
    }

    public function process() : void {
        $this->add_activity(sending_test_activity::get_name());
    }
}