public async Task AddOrInsertCachedItemAsync()
{
ObjectCache cache = MemoryCache.Default;
var policy = new CacheItemPolicy()
{
SlidingExpiration = TimeSpan.FromMinutes(1)
};
var value = await cache.AddOrGetExistingAsync <int>("foo", async() => { await Task.Delay(100); return(1); }, policy);
Assert.AreEqual(1, value);
}