public void CachingDisabledNegativeCacheEnabled()
        {
            CacheSettings settings = new CacheSettings()
            {
                Cache = false,
                NegativeCache = true,
                CacheTTLSeconds = 60,
                Name = "ABC"
            }; 

            Assert.Throws(typeof(InvalidOperationException), () => settings.Validate());
            Assert.Throws(typeof(InvalidOperationException), () => new CertificateCache(settings)); 
        }