public function testStaleWhileRevalidateHeader()
{
$this->client->get('http://test.com/stale-while-revalidate');
sleep(2);
$response = $this->client->get('http://test.com/stale-while-revalidate');
$this->assertEquals(CacheMiddleware::HEADER_CACHE_STALE, $response->getHeaderLine(CacheMiddleware::HEADER_CACHE_INFO));
// Do that at the end of the php script...
$this->cache->purgeReValidation();
$response = $this->client->get('http://test.com/stale-while-revalidate');
$this->assertEquals(CacheMiddleware::HEADER_CACHE_HIT, $response->getHeaderLine(CacheMiddleware::HEADER_CACHE_INFO));
}