public async Task FailedToSaveNewSupplier_AddSupplier_ReturnBadRequest()
        {
            var supplierModel = new SupplierModel();

            var response = await _suppliersController.AddSupplier(supplierModel);

            Assert.IsType <ActionResult <SupplierModel> >(response);
            Assert.IsType <BadRequestResult>(response.Result);
            _supplierService.Verify(s => s.Add(It.IsAny <Supplier>()));
        }