feat: add support for carrier open endpoint (#671)

# Description

- Adds support for FedexDefaultAccount, GofoWalletAccount,
UpsDapAccount, UniUniWalletAccount, and VehoWalletAccount by properly
routing carrier-account create requests to the /carrier_accounts/open
endpoint.

# Testing

- Adds new parametrized test to ensure all custom url carrier accounts
route properly

# Pull Request Type

Please select the option(s) that are relevant to this PR.

- [ ] Bug fix (non-breaking change which fixes an issue)
- [x] New feature (non-breaking change which adds functionality)
- [ ] Breaking change (fix or feature that would cause existing
functionality to not work as expected)
- [ ] Improvement (fixing a typo, updating readme, renaming a variable
name, etc)

---------

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: Justintime50

CHANGELOG.md

@@ -7,6 +7,7 @@
   - Makes `ReferralCustomer.RetrieveEasypostStripeApiKey` public to help facilitate adding credit cards using Stripe.js
 - Correctly passes `end_shipper_id` param instead of `end_shipper` in shipment buy calls (closes [669](https://github.com/EasyPost/easypost-csharp/issues/669))
 - Add `Surcharge` model and `Surcharges` property to `Rate` class
+- Adds support for `FedexDefaultAccount`, `GofoWalletAccount`, `UpsDapAccount`, `UniUniWalletAccount`, and `VehoWalletAccount` by properly routing carrier-account create requests to the `/carrier_accounts/open` endpoint
 
 ## v7.10.0 (2026-07-24)
 

EasyPost.Tests/ServicesTests/CarrierAccountServiceTest.cs

@@ -50,28 +50,29 @@ public async Task TestCreate()
             Assert.Equal("DhlEcsAccount", carrierAccount.Type);
         }
 
-        [Fact]
+        [Theory]
         [CrudOperations.Create]
         [Testing.Parameters]
-        public async Task TestCreateWithCustomWorkflow()
+        [InlineData("FedexAccount")]
+        [InlineData("FedexSmartpostAccount")]
+        [InlineData("AmazonShippingAccount")]
+        [InlineData("UpsAccount")]
+        [InlineData("UpsMailInnovationsAccount")]
+        [InlineData("UpsSurepostAccount")]
+        [InlineData("UspsShipAccount")]
+        [InlineData("FedexDefaultAccount")]
+        [InlineData("GofoWalletAccount")]
+        [InlineData("UpsDapAccount")]
+        [InlineData("UniUniWalletAccount")]
+        [InlineData("VehoWalletAccount")]
+        public async Task TestCreateWithCustomWorkflow(string carrierType)
         {
             UseVCR("create_with_custom_workflow");
 
-            //  FedEx or UPS should trigger a function error since not supported by legacy parameter method
-            try
-            {
-                Dictionary<string, object> parameters = Fixtures.BasicCarrierAccount;
-                parameters["type"] = CarrierAccountType.FedEx.Name;
-                parameters["registration_data"] = new Dictionary<string, object>();
+            Dictionary<string, object> parameters = Fixtures.BasicCarrierAccount;
+            parameters["type"] = carrierType;
 
-                CarrierAccount carrierAccount = await Client.CarrierAccount.Create(parameters);
-                CleanUpAfterTest(carrierAccount.Id);
-            }
-            catch (InvalidFunctionError e)
-            {
-                // Function should have been halted due to incompatible carrier account type
-                Assert.NotNull(e);
-            }
+            await Assert.ThrowsAsync<InvalidFunctionError>(async () => await Client.CarrierAccount.Create(parameters));
         }
 
         [Fact]

EasyPost.Tests/ServicesTests/WithParameters/CarrierAccountServiceTest.cs

@@ -1,11 +1,14 @@
 using System.Collections.Generic;
+using System.IO;
+using System.Linq;
 using System.Threading.Tasks;
 using EasyPost.Exceptions.API;
 using EasyPost.Exceptions.General;
 using EasyPost.Models.API;
 using EasyPost.Tests._Utilities;
 using EasyPost.Tests._Utilities.Attributes;
 using EasyPost.Utilities.Internal.Attributes;
+using Newtonsoft.Json.Linq;
 using Xunit;
 
 namespace EasyPost.Tests.ServicesTests.WithParameters
@@ -110,6 +113,28 @@ public async Task TestCreateUps()
             Assert.StartsWith("ca_", carrierAccount.Id);
         }
 
+        [Theory]
+        [CrudOperations.Create]
+        [Testing.Parameters]
+        [MemberData(nameof(CreateUrlRoutingData))]
+        public async Task TestCreateUrlRouting(Parameters.CarrierAccount.ACreate parameters, string cassetteName, string expectedEndpoint, string expectedBodyKey)
+        {
+            UseVCR(cassetteName);
+
+            try
+            {
+                CarrierAccount carrierAccount = await Client.CarrierAccount.Create(parameters);
+                CleanUpAfterTest(carrierAccount.Id);
+            }
+            catch (ApiError error)
+            {
+                Assert.NotEqual(404, error.StatusCode);
+                Assert.NotEqual(500, error.StatusCode);
+            }
+
+            AssertCassetteRequest(cassetteName, expectedEndpoint, expectedBodyKey);
+        }
+
         [Fact]
         [CrudOperations.Create]
         [Testing.Exception]
@@ -196,6 +221,63 @@ public async Task TestUpdateUps()
 
         #endregion
 
+        public static IEnumerable<object[]> CreateUrlRoutingData()
+        {
+            yield return new object[] { Fixtures.Parameters.CarrierAccounts.CreateFedEx(new Dictionary<string, object>()), "create_url_routing_fedex", "/carrier_accounts/register", "carrier_account" };
+            yield return new object[] { CreateFedExSmartPostParameters(), "create_url_routing_fedex_smartpost", "/carrier_accounts/register", "carrier_account" };
+            yield return new object[] { new Parameters.CarrierAccount.CreateFedExDefault(), "create_url_routing_fedex_default", "/carrier_accounts/open", "carrier_account" };
+            yield return new object[] { new Parameters.CarrierAccount.CreateGofoWallet(), "create_url_routing_gofo_wallet", "/carrier_accounts/open", "carrier_account" };
+            yield return new object[] { new Parameters.CarrierAccount.CreateUpsDap(), "create_url_routing_ups_dap", "/carrier_accounts/open", "carrier_account" };
+            yield return new object[] { new Parameters.CarrierAccount.CreateUniUniWallet(), "create_url_routing_uniuni_wallet", "/carrier_accounts/open", "carrier_account" };
+            yield return new object[] { new Parameters.CarrierAccount.CreateVehoWallet(), "create_url_routing_veho_wallet", "/carrier_accounts/open", "carrier_account" };
+            yield return new object[] { new Parameters.CarrierAccount.CreateOauth { Type = CarrierAccountType.AmazonShippingAccount.Name }, "create_url_routing_amazon_shipping", "/carrier_accounts/register_oauth", "carrier_account_oauth_registrations" };
+            yield return new object[] { Fixtures.Parameters.CarrierAccounts.CreateUps(new Dictionary<string, object>()), "create_url_routing_ups", "/carrier_accounts/register_oauth", "carrier_account_oauth_registrations" };
+            yield return new object[] { new Parameters.CarrierAccount.CreateUpsMailInnovations { AccountNumber = "123456789" }, "create_url_routing_ups_mail_innovations", "/carrier_accounts/register_oauth", "carrier_account_oauth_registrations" };
+            yield return new object[] { new Parameters.CarrierAccount.CreateUpsSurePost { AccountNumber = "123456789" }, "create_url_routing_ups_surepost", "/carrier_accounts/register_oauth", "carrier_account_oauth_registrations" };
+            yield return new object[] { new Parameters.CarrierAccount.CreateOauth { Type = CarrierAccountType.UspsShipAccount.Name }, "create_url_routing_usps_ship", "/carrier_accounts/register_oauth", "carrier_account_oauth_registrations" };
+        }
+
+        private static Parameters.CarrierAccount.CreateFedExSmartPost CreateFedExSmartPostParameters()
+        {
+            return new Parameters.CarrierAccount.CreateFedExSmartPost
+            {
+                AccountNumber = "123456789",
+                HubId = "1234",
+                CorporateAddressCity = "San Francisco",
+                CorporateAddressCountryCode = "US",
+                CorporateAddressPostalCode = "94105",
+                CorporateAddressState = "CA",
+                CorporateAddressStreet = "345 California St",
+                CorporateCompanyName = "EasyPost",
+                CorporateEmailAddress = "me@example.com",
+                CorporateFirstName = "Demo",
+                CorporateLastName = "User",
+                CorporateJobTitle = "Developer",
+                CorporatePhoneNumber = "5555555555",
+                ShippingAddressCity = "San Francisco",
+                ShippingAddressCountryCode = "US",
+                ShippingAddressPostalCode = "94105",
+                ShippingAddressState = "CA",
+                ShippingAddressStreet = "345 California St",
+            };
+        }
+
+        private static void AssertCassetteRequest(string cassetteName, string expectedEndpoint, string expectedBodyKey)
+        {
+            string cassettePath = Path.GetFullPath(Path.Combine(TestUtils.GetSourceFileDirectory(), "..", "..", "cassettes", "carrier_account_service_with_parameters", $"{cassetteName}.json"));
+            string cassetteJson = File.ReadAllText(cassettePath);
+            JArray interactions = JArray.Parse(cassetteJson);
+            JToken? interaction = interactions.FirstOrDefault();
+
+            Assert.NotNull(interaction);
+
+            string? requestUri = interaction!["Request"]?["Uri"]?.Value<string>();
+            string? requestBody = interaction["Request"]?["Body"]?.Value<string>();
+
+            Assert.EndsWith(expectedEndpoint, requestUri);
+            Assert.Contains(expectedBodyKey, requestBody);
+        }
+
         #endregion
     }
 }