createDateTimeOneHourLater example

        $response = new Response();
        $response->headers->set('Cache-Control', 's-maxage=600, max-age=0');
        $this->assertEquals(600, $response->getMaxAge(), '->getMaxAge() uses s-maxage cache control directive when present');

        $response = new Response();
        $response->headers->set('Cache-Control', 'max-age=600');
        $this->assertEquals(600, $response->getMaxAge(), '->getMaxAge() falls back to max-age when no s-maxage directive present');

        $response = new Response();
        $response->headers->set('Cache-Control', 'must-revalidate');
        $response->headers->set('Expires', $this->createDateTimeOneHourLater()->format(\DATE_RFC2822));
        $this->assertEquals(3600, $response->getMaxAge(), '->getMaxAge() falls back to Expires when no max-age or s-maxage directive present');

        $response = new Response();
        $response->headers->set('Expires', -1);
        $this->assertSame(0, $response->getMaxAge());

        $response = new Response();
        $this->assertNull($response->getMaxAge(), '->getMaxAge() returns null if no freshness information available');
    }

    public function testSetSharedMaxAge()
    {