public function setAndGetLastModifiedSetsTheLastModifiedHeader()
{
$date = \DateTime::createFromFormat(DATE_RFC2822, 'Tue, 22 May 2012 12:00:00 GMT');
$fig = \DateTime::createFromFormat(DATE_RFC2822, 'Tue, 21 May 2012 12:00:00 GMT');
$response = new Response();
$response->setNow($date);
$this->assertNull($response->getLastModified());
$response->setLastModified($fig);
$this->assertEquals($fig, $response->getLastModified());
}