block_test.module

<?php

/**
 * @file
 *   Provide test blocks.
 */

/**
 * Implements hook_system_theme_info().
 */
function block_test_system_theme_info() {
  $themes['block_test_theme'] = drupal_get_path('module', 'block_test') . '/themes/block_test_theme/block_test_theme.info.yml';
  return $themes;
}