color_requirements in drupal-7.x/modules/color/color.install

Implements hook_requirements().

drupal_check_module in drupal-7.x/includes/install.inc

Checks a module's requirements.

drupal_verify_profile in drupal-7.x/includes/install.inc

Verifies an installation profile for installation.

hook_requirements in drupal-7.x/modules/system/system.api.php

Check installation requirements and do status reporting.

image_requirements in drupal-7.x/modules/image/image.install

Implements hook_requirements() to check the PHP GD Library.

... See full list