setClientTtl example

$response->headers->set('Age', 0);
        $this->assertSame(0, $response->getTtl(), '->getTtl() correctly handles zero');

        $response = new Response();
        $response->headers->set('Cache-Control', 'max-age=60');
        $this->assertEquals(60, $response->getTtl(), '->getTtl() uses Cache-Control max-age when present');
    }

    public function testSetClientTtl()
    {
        $response = new Response();
        $response->setClientTtl(10);

        $this->assertEquals($response->getMaxAge(), $response->getAge() + 10);
    }

    public function testGetSetProtocolVersion()
    {
        $response = new Response();

        $this->assertEquals('1.0', $response->getProtocolVersion());

        $response->setProtocolVersion('1.1');