public void ContainsKey()
{
TimeSpan cacheLifeTime = TimeSpan.FromMinutes(5);
MemoryCachingService service = new MemoryCachingService(cacheLifeTime);
string cachableKey = this.cachableKey;
Foobar cachable = GetCachableObject();
service.Cache <Foobar>(cachableKey, cachable);
Assert.Single(service);;
Assert.True(service.ContainsKey(cachableKey));
}