fix: add end to end test for vision

tests/AnthropicClient.Tests/AnthropicClient.Tests.csproj

@@ -54,5 +54,11 @@
       <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
     </None>
   </ItemGroup>
+  
+  <ItemGroup>
+    <None Update="Files/**">
+      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
+    </None>
+  </ItemGroup>
 
 </Project>

tests/AnthropicClient.Tests/EndToEnd/AnthropicApiClientTests.cs

@@ -56,4 +56,41 @@ public class ClientTests(ConfigurationFixture configFixture) : EndToEndTest(conf
       }
     }
   }
+
+  [Fact]
+  public async Task CreateMessageAsync_WhenImageIsSent_ItShouldReturnResponse()
+  {
+    var imagePath = Path.Combine(Directory.GetCurrentDirectory(), "Files", "elephant.jpg");
+    var mediaType = "image/jpeg";
+    var imageBytes = await File.ReadAllBytesAsync(imagePath);
+    var base64Image = Convert.ToBase64String(imageBytes);
+
+    var request = new MessageRequest(
+      model: AnthropicModels.Claude3Haiku,
+      messages: [
+        new(MessageRole.User, [
+          new ImageContent(mediaType, base64Image),
+          new TextContent("What is in this image?")
+        ]),
+      ]
+    );
+
+    var result = await _client.CreateMessageAsync(request);
+
+    result.IsSuccess.Should().BeTrue();
+    result.Value.Should().BeOfType<MessageResponse>();
+    result.Value.Content.Should().NotBeNullOrEmpty();
+    
+    var text = result.Value.Content.Aggregate("", (acc, content) => 
+    {
+      if (content is TextContent textContent)
+      {
+        acc += textContent.Text;
+      }
+
+      return acc;
+    });
+
+    text.Should().Contain("elephant");
+  }
 }