refactor(openai): 重新实现请求加密 XML 序列化的方式

test/SKIT.FlurlHttpClient.Wechat.OpenAI.UnitTests/TestCase_ApiExecuteDialogTests.cs

@@ -0,0 +1,17 @@
+using System.Threading.Tasks;
+using Xunit;
+
+namespace SKIT.FlurlHttpClient.Wechat.OpenAI.UnitTests
+{
+    public class TestCase_ApiExecuteDialogTests
+    {
+        [Fact(DisplayName = "测试用例：调用 API [POST] /sign/{TOKEN}")]
+        public async Task TestExecuteSign()
+        {
+            var request = new Models.SignRequest() { UserId = "TEST_USERID" };
+            var response = await TestClients.Instance.ExecuteSignAsync(request);
+
+            Assert.NotNull(response.Signature);
+        }
+    }
+}