Add test to confirm user behavior in Issue 552

Author: BenjaminDavidPinter

tests/Assistants/AssistantsTests.cs

@@ -1,10 +1,4 @@
-using NUnit.Framework;
-using NUnit.Framework.Internal;
-using OpenAI.Assistants;
-using OpenAI.Files;
-using OpenAI.Tests.Utility;
-using OpenAI.VectorStores;
-using System;
+using System;
 using System.ClientModel;
 using System.ClientModel.Primitives;
 using System.Collections.Generic;
@@ -13,6 +7,12 @@
 using System.Text.Json;
 using System.Threading;
 using System.Threading.Tasks;
+using NUnit.Framework;
+using NUnit.Framework.Internal;
+using OpenAI.Assistants;
+using OpenAI.Files;
+using OpenAI.Tests.Utility;
+using OpenAI.VectorStores;
 using static OpenAI.Tests.TestHelpers;
 
 namespace OpenAI.Tests.Assistants;
@@ -1028,6 +1028,45 @@ This file describes the favorite foods of several people.
         });
     }
 
+    [Test]
+    public async Task FileOnMessageWorks()
+    {
+        // First, we need to upload a simple test file.
+        OpenAIFileClient fileClient = GetTestClient<OpenAIFileClient>(TestScenario.Files);
+        OpenAIFile testFile = fileClient.UploadFile(
+            BinaryData.FromString("""
+            This file describes the favorite foods of several people.
+
+            Summanus Ferdinand: tacos
+            Tekakwitha Effie: pizza
+            Filip Carola: cake
+            """).ToStream(),
+            "favorite_foods.txt",
+            FileUploadPurpose.Assistants);
+        Validate(testFile);
+
+        AssistantClient client = GetTestClient();
+
+        var thread = client.CreateThread();
+        var assistant = client.CreateAssistant("gpt-4o-mini");
+
+        var message = await client.CreateMessageAsync(
+        thread.Value.Id,
+        MessageRole.User,
+        new[] {
+            MessageContent.FromText("What is this file?"),
+        },
+        new MessageCreationOptions()
+        {
+            Attachments = [
+                new MessageCreationAttachment(testFile.Id, new List<ToolDefinition>() { ToolDefinition.CreateFileSearch() }),
+                new MessageCreationAttachment(testFile.Id, new List<ToolDefinition>() { ToolDefinition.CreateCodeInterpreter() })
+                ]
+        });
+
+        var result = client.CreateRunStreamingAsync(thread.Value.Id, assistant.Value.Id);
+    }
+
     [Test]
     public void FileSearchStreamingWorksSync()
     {