materio-base-d7/modules/simpletest/tests/boot_test_1.module

<?php

/**
 * @file
 * Tests calling module_implements() during hook_boot() invocation.
 */

/**
 * Implements hook_boot().
 */
function boot_test_1_boot() {
  // Calling module_implements during hook_boot() will return "vital" modules
  // only, and this list of modules will be statically cached.
  module_implements('help');
  // Define a special path to test that the static cache isn't written away
  // if we exit before having completed the bootstrap.
  if ($_GET['q'] == 'early_exit') {
    module_implements_write_cache();
    exit();
  }
}