public void WhenAddHistory_ThenAddsHistory()
            {
                var datum = DateTime.UtcNow.ToNearestSecond();

                cacheClient.Setup(cc => cc.Get <object>("akey"))
                .Returns(new WebhookSubscription
                {
                    Id          = "asubscriptionid",
                    Event       = "aneventname",
                    CreatedById = "auserid"
                });
                var result = new SubscriptionDeliveryResult
                {
                    Id = "aresultid",
                    AttemptedDateUtc = datum
                };

                store.Add("asubscriptionid", result);

                cacheClient.Verify(cc => cc.Add(CacheClientSubscriptionStore.FormatHistoryCacheKey("auserid", "aneventname", "aresultid"), It.Is <SubscriptionDeliveryResult>(sub =>
                                                                                                                                                                              (sub.Id == "aresultid") &&
                                                                                                                                                                              (sub.AttemptedDateUtc == datum))));
            }