Symfony\Component\HttpFoundation\Tests\ResponseTest::testExpire PHP Method

    public function testExpire()
    {
        $response = new Response();
        $response->headers->set('Cache-Control', 'max-age=100');
        $response->expire();
        $this->assertEquals(100, $response->headers->get('Age'), '->expire() sets the Age to max-age when present');

        $response = new Response();
        $response->headers->set('Cache-Control', 'max-age=100, s-maxage=500');
        $response->expire();
        $this->assertEquals(500, $response->headers->get('Age'), '->expire() sets the Age to s-maxage when both max-age and s-maxage are present');

        $response = new Response();
        $response->headers->set('Cache-Control', 'max-age=5, s-maxage=500');
        $response->headers->set('Age', '1000');
        $response->expire();
        $this->assertEquals(1000, $response->headers->get('Age'), '->expire() does nothing when the response is already stale/expired');

        $response = new Response();
        $response->expire();
        $this->assertFalse($response->headers->has('Age'), '->expire() does nothing when the response does not include freshness information');

        $response = new Response();
        $response->headers->set('Expires', -1);
        $response->expire();
        $this->assertNull($response->headers->get('Age'), '->expire() does not set the Age when the response is expired');
    }