public function testSetLastModifiedWithDateTimeObject() { $response = new Response(new App()); $response->setLastModified(DateTime::createFromFormat('Y-m-d', '2000-03-10')); $date = DateTime::createFromFormat('Y-m-d', '2000-03-10'); $date->setTimezone(new DateTimeZone('UTC')); $header = $response->getHeaderLine('Last-Modified'); $this->assertEquals($date->format('D, d M Y H:i:s') . ' GMT', $header); }