public void SubscriptionsService_DeleteUserSubscription_calls_Delete_method()
        {
            int  purchaseId     = 74;
            int  subscriptionId = 17;
            bool isDeleteCalled = false;

            var mock = new Mock <IUnitOfWork>();

            mock.Setup(a => a.UserSubscriptions.Find(It.IsAny <Func <UserSubscription, bool> >()))
            .Returns(new List <UserSubscription>
            {
                new UserSubscription {
                    Id = 21, PurchaseId = purchaseId, SubscriptionId = subscriptionId
                }
            });
            mock.Setup(a => a.UserSubscriptions.Delete(It.IsAny <int>())).Callback(() => isDeleteCalled = true);

            service = new SubscriptionsService(mock.Object);
            service.DeleteUserSubscription(purchaseId, subscriptionId);

            Assert.IsTrue(isDeleteCalled);
        }