public void SubscriptionsService_GetCurrentPurchase_result_not_null()
        {
            int id   = 85;
            var mock = new Mock <IUnitOfWork>();

            mock.Setup(a => a.Purchases.Get(id)).Returns(new Purchase());

            service = new SubscriptionsService(mock.Object);
            var result = service.GetCurrentPurchase(id);

            Assert.IsNotNull(result);
        }