public async Task IdOfNonexistentSupplier_UpdateSupplier_SupplierNotUpdated()
        {
            const int supplierId    = -1;
            var       supplierModel = new SupplierModel();

            var response = await _suppliersController.UpdateSupplier(supplierId, supplierModel);

            Assert.IsType <ActionResult <SupplierModel> >(response);
            Assert.IsType <NotFoundResult>(response.Result);
        }