Backend must only guarantee that the increment is made, but the final value
may not be current + $value due to concurrent accesses.
public function increment(CacheAbstract $cache) { $key = new CacheKey('increment', 'it'); $cache->delete($key); $this->assertEquals(5, $cache->increment(1, $key, 5)); $this->assertEquals(6, $cache->increment(1, $key, 5)); }