addtocalendar-8.x-3.x-dev/tests/modules/addtocalendar_test/addtocalendar_test.module

<?php

/**
 * Prevent external js from being requested.
 *
 * Implements hook_library_info_alter().
 */
function addtocalendar_test_library_info_alter(&$libraries, $extension) {
  if ($extension === 'addtocalendar') {
    $libraries['base']['js'] = [];
  }
}