WordPress: Required plugins hook.

required-plugins.php

<?php

add_action('admin_notices', function()
{
    $plugin_messages = array();

    include_once( ABSPATH . 'wp-admin/includes/plugin.php' );

    $required_plugins = [
        'wordpress-seo/wp-seo.php' => 'Yoast SEO',
        'sendgrid-email-delivery-simplified/wpsendgrid.php' => 'SendGrid',
        'w3-total-cache/w3-total-cache.php' => 'W3 Total Cache',
        'woocommerce/woocommerce.php' => 'W3 Total Cache',
    ];

    foreach ($required_plugins as $plugin_slug => $plugin_label)
    {
        if(!is_plugin_active($plugin_slug))
        {
            $plugin_messages[] = "Activate plugin: {$plugin_label}.";
        }
    }


    if(count($plugin_messages) > 0)
    {
        echo '<div id="message" class="error">';

            foreach($plugin_messages as $message)
            {
                echo '<p><strong>'.$message.'</strong></p>';
            }

        echo '</div>';
    }
});