private async Task <SupplierInvoiceExternalURLConnection> CreateEntity(int supplierInvoiceNumber)
        {
            var request = new FortnoxApiRequest(this.connectionSettings.AccessToken, this.connectionSettings.ClientSecret);

            return
                (await SupplierInvoiceExternalURLConnectionsService.CreateSupplierInvoiceExternalURLConnectionsAsync(
                     request,
                     new SupplierInvoiceExternalURLConnection
            {
                SupplierInvoiceNumber = supplierInvoiceNumber,
                ExternalURLConnection = ExternalUrl,
            }
                     ));
        }
        public async Task CreateSupplierInvoiceExternalUrlConnectionTest()
        {
            var request  = new FortnoxApiRequest(this.connectionSettings.AccessToken, this.connectionSettings.ClientSecret);
            var response =
                await SupplierInvoiceExternalURLConnectionsService.CreateSupplierInvoiceExternalURLConnectionsAsync(
                    request,
                    new SupplierInvoiceExternalURLConnection
            {
                SupplierInvoiceNumber = 1,
                ExternalURLConnection = ExternalUrl,
            }
                    );

            await DeleteEntity(response.Id);

            Assert.AreEqual(ExternalUrl, response.ExternalURLConnection);
            Assert.AreEqual(1, response.SupplierInvoiceNumber);
        }