Menu callback: displays the 'Add new entity_test' form.
string $entity_type: Name of the entity type for which a create form should be displayed.
array The processed form for a new entity_test.
function entity_test_add($entity_type) {
drupal_set_title(t('Create an @type', array(
'@type' => $entity_type,
)));
$entity = entity_create($entity_type, array());
return entity_get_form($entity);
}