public function getAllAddsCacheControlHeaderIfCacheDirectivesHaveBeenSet()
{
$expectedFields = ['Last-Modified' => ['Tue, 24 May 2012 12:00:00 +0000']];
$headers = new Headers($expectedFields);
$this->assertEquals($expectedFields, $headers->getAll());
$expectedFields['Cache-Control'] = ['public, max-age=60'];
$headers->setCacheControlDirective('public');
$headers->setCacheControlDirective('max-age', 60);
$this->assertEquals($expectedFields, $headers->getAll());
}