diff --git a/tests/AnthropicClient.Tests/EndToEnd/AnthropicApiClientTests.cs b/tests/AnthropicClient.Tests/EndToEnd/AnthropicApiClientTests.cs
index fe5560c..f56d165 100644
--- a/tests/AnthropicClient.Tests/EndToEnd/AnthropicApiClientTests.cs
+++ b/tests/AnthropicClient.Tests/EndToEnd/AnthropicApiClientTests.cs
@@ -1,9 +1,6 @@
 namespace AnthropicClient.Tests.EndToEnd;
 
-public class ClientTests(
-  HttpClientFixture httpClientFixture,
-  ConfigurationFixture configFixture
-) : EndToEndTest(httpClientFixture, configFixture)
+public class ClientTests(ConfigurationFixture configFixture) : EndToEndTest(configFixture)
 {
   [Fact]
   public async Task CreateChatMessage_WhenCalled_ItShouldReturnChatResponse()
diff --git a/tests/AnthropicClient.Tests/EndToEnd/EndToEndTest.cs b/tests/AnthropicClient.Tests/EndToEnd/EndToEndTest.cs
index b4cc22d..6e9b19b 100644
--- a/tests/AnthropicClient.Tests/EndToEnd/EndToEndTest.cs
+++ b/tests/AnthropicClient.Tests/EndToEnd/EndToEndTest.cs
@@ -1,9 +1,6 @@
 namespace AnthropicClient.Tests.EndToEnd;
 
-public class EndToEndTest(
-  HttpClientFixture httpClientFixture,
-  ConfigurationFixture configFixture
-) : IClassFixture<HttpClientFixture>, IClassFixture<ConfigurationFixture>
+public class EndToEndTest(ConfigurationFixture configFixture) : IClassFixture<ConfigurationFixture>
 {
-  protected readonly AnthropicApiClient _client = new(configFixture.AnthropicApiKey, httpClientFixture.HttpClient);
+  protected readonly AnthropicApiClient _client = new(configFixture.AnthropicApiKey, new());
 }
\ No newline at end of file
diff --git a/tests/AnthropicClient.Tests/Unit/Models/AnthropicResultTests.cs b/tests/AnthropicClient.Tests/Unit/Models/AnthropicResultTests.cs
index 715e03a..fa02473 100644
--- a/tests/AnthropicClient.Tests/Unit/Models/AnthropicResultTests.cs
+++ b/tests/AnthropicClient.Tests/Unit/Models/AnthropicResultTests.cs
@@ -6,25 +6,25 @@ public class AnthropicResultTests
   public void Success_WhenCalled_ItShouldReturnSuccessResult()
   {
     var value = "success";
-    var requestId = Guid.NewGuid().ToString();
+    var headers = new AnthropicHeaders();
 
-    var actual = AnthropicResult<string>.Success(value, requestId);
+    var actual = AnthropicResult<string>.Success(value, headers);
 
     actual.IsSuccess.Should().BeTrue();
     actual.Value.Should().Be(value);
-    actual.RequestId.Should().Be(requestId);
+    actual.Headers.Should().Be(headers);
   }
 
   [Fact]
   public void Failure_WhenCalled_ItShouldReturnFailureResult()
   {
     var error = new AnthropicError(new AuthenticationError("message"));
-    var requestId = Guid.NewGuid().ToString();
+    var headers = new AnthropicHeaders();
 
-    var actual = AnthropicResult<string>.Failure(error, requestId);
+    var actual = AnthropicResult<string>.Failure(error, headers);
 
     actual.IsSuccess.Should().BeFalse();
     actual.Error.Should().Be(error);
-    actual.RequestId.Should().Be(requestId);
+    actual.Headers.Should().Be(headers);
   }
 }
\ No newline at end of file