drupal/modules/locale/tests/locale_test.module

<?php
// $Id$

/**
 * @file
 * Mock module for locale layer tests.
 */

/**
 * Implements hook_locale().
 */
function locale_test_locale($op = 'groups') {
  switch ($op) {
    case 'groups':
      return array('custom' => t('Custom'));
  }
}

/**
 * Implements hook_boot().
 *
 * For testing domain language negotiation, we fake it by setting
 * the HTTP_HOST here
 */
function locale_test_boot() {
  if (variable_get('locale_test_domain')) {
    $_SERVER['HTTP_HOST'] = variable_get('locale_test_domain');
  }
}

/**
 * Implements hook_language_types_info_alter().
 */
function locale_test_language_types_info_alter(array &$language_types) {
  if (variable_get('locale_test_content_language_type', FALSE)) {
    $language_types[LANGUAGE_TYPE_CONTENT] = array(
      'name' => t('Content'),
      'description' => t('Order of language detection methods for content. If a version of content is available in the detected language, it will be displayed.'),
    );
  }
}