Tests the Update Manager module when the update server returns 503 errors.
function testServiceUnavailable() {
$this
->refreshUpdateStatus(array(), '503-error');
// Ensure that no "Warning: SimpleXMLElement..." parse errors are found.
$this
->assertNoText('SimpleXMLElement');
$this
->assertUniqueText(t('Failed to get available update data for one project.'));
}