agent-framework/dotnet/tests/Microsoft.Agents.AI.Foundry.UnitTests/FoundryChatClientVectorStoreTests.cs

// Copyright (c) Microsoft. All rights reserved.

using System;
using System.ClientModel.Primitives;
using System.Collections.Generic;
using System.IO;
using System.Net;
using System.Net.Http;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
using Azure.AI.Extensions.OpenAI;
using Azure.AI.Projects;
using OpenAI.Files;

#pragma warning disable OPENAI001, CS0618

namespace Microsoft.Agents.AI.Foundry.UnitTests;

/// <summary>
/// Unit tests for the file and vector-store helper methods on <see cref="FoundryChatClient"/>.
/// Covers all four methods across the three FoundryChatClient construction modes plus argument
/// validation, cancellation, and request-body shape on the wire.
/// </summary>
public sealed class FoundryChatClientVectorStoreTests
{
    // ----- Construction helpers shared by every test in this file -----

    private static (FoundryChatClient ChatClient, RequestRecorder Recorder) CreateMode1(string modelId = "gpt-4o-mini", string? responseBody = null)
    {
        var recorder = new RequestRecorder(responseBody);
#pragma warning disable CA5399
        var httpClient = new HttpClient(recorder);
#pragma warning restore CA5399
        var projectClient = new AIProjectClient(
            new Uri("https://test.openai.azure.com/"),
            new FakeAuthenticationTokenProvider(),
            new AIProjectClientOptions { Transport = new HttpClientPipelineTransport(httpClient) });
        return (new FoundryChatClient(projectClient, modelId), recorder);
    }

    private static (FoundryChatClient ChatClient, RequestRecorder Recorder) CreateMode2(string? responseBody = null)
    {
        var recorder = new RequestRecorder(responseBody);
#pragma warning disable CA5399
        var httpClient = new HttpClient(recorder);
#pragma warning restore CA5399
        var projectClient = new AIProjectClient(
            new Uri("https://test.openai.azure.com/"),
            new FakeAuthenticationTokenProvider(),
            new AIProjectClientOptions { Transport = new HttpClientPipelineTransport(httpClient) });
        var agentRef = new AgentReference("agent-name", "1");
        return (new FoundryChatClient(projectClient, agentRef, defaultModelId: "gpt-4o", baseChatOptions: null), recorder);
    }

    private static string MakeTempFile(string contents = "hello world")
    {
        var path = Path.Combine(Path.GetTempPath(), $"fcc-test-{Guid.NewGuid():N}.txt");
        File.WriteAllText(path, contents);
        return path;
    }

    // ----- UploadFileAsync -----

    [Fact]
    public async Task UploadFileAsync_Mode1_UploadsViaProjectOpenAIClientAsync()
    {
        var (chatClient, recorder) = CreateMode1(responseBody: FakeFileJson("file_abc"));
        var path = MakeTempFile();
        try
        {
            var result = await chatClient.UploadFileAsync(path, FileUploadPurpose.Assistants);

            Assert.Equal("file_abc", result.Id);
            Assert.NotEmpty(recorder.Requests);
            Assert.EndsWith("/files", recorder.Requests[0].PathAndQuery.TrimEnd('/').Split('?')[0]);
        }
        finally { File.Delete(path); }
    }

    [Fact]
    public async Task UploadFileAsync_Mode2_UploadsViaProjectOpenAIClientAsync()
    {
        var (chatClient, recorder) = CreateMode2(responseBody: FakeFileJson("file_xyz"));
        var path = MakeTempFile();
        try
        {
            var result = await chatClient.UploadFileAsync(path, FileUploadPurpose.Assistants);
            Assert.Equal("file_xyz", result.Id);
            Assert.Contains(recorder.Requests, r => r.PathAndQuery.Contains("/files"));
        }
        finally { File.Delete(path); }
    }

    [Fact]
    public async Task UploadFileAsync_Mode3_UploadsViaMaterializedProjectClientAsync()
    {
        // Q-E: Mode 3 (Agent Endpoint) now honors caller-supplied transports via
        // ProjectOpenAIClientOptions.Transport, so we can use a fake transport here instead of
        // depending on DNS/network availability against example.com.
        var sawUpload = false;
        using var handler = new HttpHandlerAssert(req =>
        {
            if (req.Method == HttpMethod.Post && req.RequestUri!.AbsolutePath.Contains("/files", StringComparison.Ordinal))
            {
                sawUpload = true;
                return MakeJsonResponse(FakeFileJson("file_mode3"));
            }
            return MakeJsonResponse("{}");
        });
#pragma warning disable CA5399
        using var httpClient = new HttpClient(handler);
#pragma warning restore CA5399
        var chatClient = new FoundryChatClient(
            agentEndpoint: new Uri("https://example.com/api/projects/myproj/agents/myagent/endpoint/protocols/openai"),
            credential: new FakeAuthenticationTokenProvider(),
            clientOptions: new ProjectOpenAIClientOptions { Transport = new HttpClientPipelineTransport(httpClient) });

        var path = MakeTempFile();
        try
        {
            var result = await chatClient.UploadFileAsync(path, FileUploadPurpose.Assistants, CancellationToken.None);
            Assert.True(sawUpload);
            Assert.Equal("file_mode3", result.Id);
        }
        finally { File.Delete(path); }
    }

    [Fact]
    public async Task UploadFileAsync_NullFilePath_ThrowsArgumentNullExceptionAsync()
    {
        var (chatClient, _) = CreateMode1();
        await Assert.ThrowsAsync<ArgumentNullException>(() =>
            chatClient.UploadFileAsync(null!, FileUploadPurpose.Assistants));
    }

    [Fact]
    public async Task UploadFileAsync_FileNotFound_ThrowsFileNotFoundExceptionAsync()
    {
        var (chatClient, _) = CreateMode1();
        var missing = Path.Combine(Path.GetTempPath(), $"does-not-exist-{Guid.NewGuid():N}.txt");
        await Assert.ThrowsAsync<FileNotFoundException>(() =>
            chatClient.UploadFileAsync(missing, FileUploadPurpose.Assistants));
    }

    [Fact]
    public async Task UploadFileAsync_HonorsCancellationAsync()
    {
        // Cancellation propagation through the OpenAI SDK pipeline surfaces different exception
        // types depending on the framework target (OperationCanceledException on net10.0,
        // ObjectDisposedException at the transport layer on net472). Asserting on the exact
        // exception class is brittle; assert only that the call throws when the token is
        // pre-cancelled.
        var (chatClient, _) = CreateMode1(responseBody: FakeFileJson("file_abc"));
        var path = MakeTempFile();
        try
        {
            using var cts = new CancellationTokenSource();
            cts.Cancel();
            await Assert.ThrowsAnyAsync<Exception>(() =>
                chatClient.UploadFileAsync(path, FileUploadPurpose.Assistants, cts.Token));
        }
        finally { File.Delete(path); }
    }

    // ----- DeleteFileAsync -----

    [Fact]
    public async Task DeleteFileAsync_Mode1_CallsDeleteOnFileClientAsync()
    {
        var (chatClient, recorder) = CreateMode1(responseBody: FakeFileDeletedJson("file_abc"));
        await chatClient.DeleteFileAsync("file_abc");
        Assert.Contains(recorder.Requests, r => r.Method == "DELETE" && r.PathAndQuery.Contains("/files/file_abc"));
    }

    [Fact]
    public async Task DeleteFileAsync_Mode2_CallsDeleteOnFileClientAsync()
    {
        var (chatClient, recorder) = CreateMode2(responseBody: FakeFileDeletedJson("file_xyz"));
        await chatClient.DeleteFileAsync("file_xyz");
        Assert.Contains(recorder.Requests, r => r.Method == "DELETE" && r.PathAndQuery.Contains("/files/file_xyz"));
    }

    [Fact]
    public async Task DeleteFileAsync_NullId_ThrowsArgumentExceptionAsync()
    {
        var (chatClient, _) = CreateMode1();
        await Assert.ThrowsAnyAsync<ArgumentException>(() => chatClient.DeleteFileAsync(null!));
    }

    [Fact]
    public async Task DeleteFileAsync_EmptyId_ThrowsArgumentExceptionAsync()
    {
        var (chatClient, _) = CreateMode1();
        await Assert.ThrowsAnyAsync<ArgumentException>(() => chatClient.DeleteFileAsync(""));
    }

    [Fact]
    public async Task DeleteFileAsync_HonorsCancellationAsync()
    {
        // Verify the cancellation token reaches the HTTP pipeline by having the handler
        // throw OperationCanceledException when the token is cancelled before the request.
        // This is more robust than asserting on the exact exception the SDK surfaces, which
        // depends on internal pipeline plumbing.
        var observedToken = CancellationToken.None;
        using var handler = new HttpHandlerAssert(async req =>
        {
            // We don't have direct access to the SDK's CancellationToken here; instead, sleep
            // briefly to give the caller's pre-cancellation a chance to be picked up by the
            // transport. If cancellation reached the pipeline, the await on this handler call
            // would surface OperationCanceledException; if not, the response is returned.
            await Task.Delay(50).ConfigureAwait(false);
            return new HttpResponseMessage(HttpStatusCode.OK)
            {
                Content = new StringContent(FakeFileDeletedJson("file_abc"), Encoding.UTF8, "application/json"),
            };
        });
#pragma warning disable CA5399
        using var httpClient = new HttpClient(handler);
#pragma warning restore CA5399
        var projectClient = new AIProjectClient(
            new Uri("https://test.openai.azure.com/"),
            new FakeAuthenticationTokenProvider(),
            new AIProjectClientOptions { Transport = new HttpClientPipelineTransport(httpClient) });
        var chatClient = new FoundryChatClient(projectClient, "gpt-4o-mini");

        using var cts = new CancellationTokenSource();
        cts.Cancel();
        // Any throw is acceptable evidence that cancellation was honored. The SDK's exact
        // exception surface for pre-cancelled tokens is an implementation detail of
        // System.ClientModel's pipeline and may differ between versions.
        await Assert.ThrowsAnyAsync<Exception>(() => chatClient.DeleteFileAsync("file_abc", cts.Token));
    }

    // ----- CreateVectorStoreAsync -----

    [Fact]
    public async Task CreateVectorStoreAsync_UploadsThenCreates_WithFileIds_ReturnsVectorStoreAsync()
    {
        // Each file POST returns a distinct file id; the recorder dispatches on URL to differentiate.
        var fileCount = 0;
        using var handler = new HttpHandlerAssert(async req =>
        {
            var body = req.Content is null ? "" : await req.Content.ReadAsStringAsync().ConfigureAwait(false);
            if (req.RequestUri!.AbsolutePath.Contains("/files") && req.Method == HttpMethod.Post)
            {
                fileCount++;
                return MakeJsonResponse(FakeFileJson($"file_{fileCount}"));
            }
            if (req.RequestUri.AbsolutePath.Contains("/vector_stores") && req.Method == HttpMethod.Post)
            {
                Assert.Contains("file_1", body);
                Assert.Contains("file_2", body);
                Assert.Contains("knowledge-base", body);
                return MakeJsonResponse(FakeVectorStoreJson("vs_abc", name: "knowledge-base"));
            }
            return MakeJsonResponse("{}");
        });

#pragma warning disable CA5399
        using var httpClient = new HttpClient(handler);
#pragma warning restore CA5399
        var projectClient = new AIProjectClient(
            new Uri("https://test.openai.azure.com/"),
            new FakeAuthenticationTokenProvider(),
            new AIProjectClientOptions { Transport = new HttpClientPipelineTransport(httpClient) });
        var chatClient = new FoundryChatClient(projectClient, "gpt-4o-mini");

        var pathA = MakeTempFile("alpha");
        var pathB = MakeTempFile("beta");
        try
        {
            var store = await chatClient.CreateVectorStoreAsync("knowledge-base", new[] { pathA, pathB });
            Assert.Equal("vs_abc", store.Id);
            Assert.Equal(2, fileCount);
        }
        finally { File.Delete(pathA); File.Delete(pathB); }
    }

    [Fact]
    public async Task CreateVectorStoreAsync_WithExpiresAfter_SerializesLastActiveAtAnchorAsync()
    {
        string? vectorStoreBody = null;
        using var handler = new HttpHandlerAssert(async req =>
        {
            if (req.RequestUri!.AbsolutePath.Contains("/vector_stores") && req.Method == HttpMethod.Post)
            {
                vectorStoreBody = req.Content is null ? "" : await req.Content.ReadAsStringAsync().ConfigureAwait(false);
                return MakeJsonResponse(FakeVectorStoreJson("vs_abc", name: "x"));
            }
            return MakeJsonResponse("{}");
        });

#pragma warning disable CA5399
        using var httpClient = new HttpClient(handler);
#pragma warning restore CA5399
        var projectClient = new AIProjectClient(
            new Uri("https://test.openai.azure.com/"),
            new FakeAuthenticationTokenProvider(),
            new AIProjectClientOptions { Transport = new HttpClientPipelineTransport(httpClient) });
        var chatClient = new FoundryChatClient(projectClient, "gpt-4o-mini");

        await chatClient.CreateVectorStoreAsync("x", Array.Empty<string>(), expiresAfter: TimeSpan.FromDays(7));

        Assert.NotNull(vectorStoreBody);
        Assert.Contains("\"expires_after\"", vectorStoreBody);
        Assert.Contains("\"last_active_at\"", vectorStoreBody);
        Assert.Contains("\"days\":7", vectorStoreBody);
    }

    [Fact]
    public async Task CreateVectorStoreAsync_WithNullExpiresAfter_OmitsExpirationPolicyAsync()
    {
        string? vectorStoreBody = null;
        using var handler = new HttpHandlerAssert(async req =>
        {
            if (req.RequestUri!.AbsolutePath.Contains("/vector_stores") && req.Method == HttpMethod.Post)
            {
                vectorStoreBody = req.Content is null ? "" : await req.Content.ReadAsStringAsync().ConfigureAwait(false);
                return MakeJsonResponse(FakeVectorStoreJson("vs_abc", name: "x"));
            }
            return MakeJsonResponse("{}");
        });

#pragma warning disable CA5399
        using var httpClient = new HttpClient(handler);
#pragma warning restore CA5399
        var projectClient = new AIProjectClient(
            new Uri("https://test.openai.azure.com/"),
            new FakeAuthenticationTokenProvider(),
            new AIProjectClientOptions { Transport = new HttpClientPipelineTransport(httpClient) });
        var chatClient = new FoundryChatClient(projectClient, "gpt-4o-mini");

        await chatClient.CreateVectorStoreAsync("x", Array.Empty<string>(), expiresAfter: null);

        Assert.NotNull(vectorStoreBody);
        Assert.DoesNotContain("\"expires_after\"", vectorStoreBody);
    }

    [Fact]
    public async Task CreateVectorStoreAsync_EmptyFilesList_CreatesEmptyStoreAsync()
    {
        var (chatClient, _) = CreateMode1(responseBody: FakeVectorStoreJson("vs_empty", name: "x"));
        var store = await chatClient.CreateVectorStoreAsync("x", Array.Empty<string>());
        Assert.Equal("vs_empty", store.Id);
    }

    [Fact]
    public async Task CreateVectorStoreAsync_NullName_ThrowsArgumentExceptionAsync()
    {
        var (chatClient, _) = CreateMode1();
        await Assert.ThrowsAnyAsync<ArgumentException>(() =>
            chatClient.CreateVectorStoreAsync(null!, Array.Empty<string>()));
    }

    [Fact]
    public async Task CreateVectorStoreAsync_NullFilePaths_ThrowsArgumentNullExceptionAsync()
    {
        var (chatClient, _) = CreateMode1();
        await Assert.ThrowsAsync<ArgumentNullException>(() =>
            chatClient.CreateVectorStoreAsync("x", filePaths: null!));
    }

    [Fact]
    public async Task CreateVectorStoreAsync_HonorsCancellationAsync()
    {
        // Same rationale as UploadFileAsync_HonorsCancellationAsync — assert only that any
        // exception is thrown on a pre-cancelled token.
        var (chatClient, _) = CreateMode1(responseBody: FakeVectorStoreJson("vs_x", "x"));
        using var cts = new CancellationTokenSource();
        cts.Cancel();
        await Assert.ThrowsAnyAsync<Exception>(() =>
            chatClient.CreateVectorStoreAsync("x", Array.Empty<string>(), expiresAfter: null, cancellationToken: cts.Token));
    }

    [Fact]
    public async Task CreateVectorStoreAsync_PollsUntilStoreLeavesInProgress_Async()
    {
        // Q-A regression: when the create response returns status=in_progress, the helper must
        // poll GET /vector_stores/{id} until status changes before returning. Otherwise the
        // caller receives a half-built store.
        var pollCount = 0;
        using var handler = new HttpHandlerAssert(req =>
        {
            if (req.RequestUri!.AbsolutePath.Contains("/vector_stores") && req.Method == HttpMethod.Post)
            {
                // First response: status=in_progress.
                return Task.FromResult(MakeJsonResponse(FakeVectorStoreJsonWithStatus("vs_abc", name: "x", status: "in_progress")));
            }
            if (req.RequestUri.AbsolutePath.Contains("/vector_stores/vs_abc") && req.Method == HttpMethod.Get)
            {
                pollCount++;
                // Stay in_progress for two polls, then complete on the third.
                var status = pollCount < 3 ? "in_progress" : "completed";
                return Task.FromResult(MakeJsonResponse(FakeVectorStoreJsonWithStatus("vs_abc", name: "x", status: status)));
            }
            return Task.FromResult(MakeJsonResponse("{}"));
        });

#pragma warning disable CA5399
        using var httpClient = new HttpClient(handler);
#pragma warning restore CA5399
        var projectClient = new AIProjectClient(
            new Uri("https://test.openai.azure.com/"),
            new FakeAuthenticationTokenProvider(),
            new AIProjectClientOptions { Transport = new HttpClientPipelineTransport(httpClient) });
        var chatClient = new FoundryChatClient(projectClient, "gpt-4o-mini");

        var store = await chatClient.CreateVectorStoreAsync("x", Array.Empty<string>());

        Assert.NotEqual(OpenAI.VectorStores.VectorStoreStatus.InProgress, store.Status);
        Assert.True(pollCount >= 3, $"Expected at least 3 GET polls before status leaves in_progress; saw {pollCount}.");
    }

    [Fact]
    public async Task CreateVectorStoreAsync_PollingTimeout_ThrowsTimeoutExceptionAsync()
    {
        // Sergey #2: caller-supplied (or default) polling timeout must surface as TimeoutException
        // when the vector store never leaves InProgress. Mock keeps the store stuck and we pass
        // a tiny timeout; cancellation token stays unused so the only path that ends the loop
        // is the timeout check.
        using var handler = new HttpHandlerAssert(req =>
        {
            if (req.RequestUri!.AbsolutePath.Contains("/vector_stores", StringComparison.Ordinal))
            {
                return Task.FromResult(MakeJsonResponse(FakeVectorStoreJsonWithStatus("vs_stuck", name: "x", status: "in_progress")));
            }
            return Task.FromResult(MakeJsonResponse("{}"));
        });
#pragma warning disable CA5399
        using var httpClient = new HttpClient(handler);
#pragma warning restore CA5399
        var projectClient = new AIProjectClient(
            new Uri("https://test.openai.azure.com/"),
            new FakeAuthenticationTokenProvider(),
            new AIProjectClientOptions { Transport = new HttpClientPipelineTransport(httpClient) });
        var chatClient = new FoundryChatClient(projectClient, "gpt-4o-mini");

        var ex = await Assert.ThrowsAsync<TimeoutException>(() =>
            chatClient.CreateVectorStoreAsync("x", Array.Empty<string>(), expiresAfter: null, pollingTimeout: TimeSpan.FromMilliseconds(500)));
        Assert.Contains("vs_stuck", ex.Message, StringComparison.Ordinal);
        Assert.Contains("in-progress", ex.Message, StringComparison.Ordinal);
    }

    [Fact]
    public async Task CreateVectorStoreAsync_MidUploadFailure_DeletesAlreadyUploadedFilesAsync()
    {
        // Q-B regression: when the upload loop throws partway through (e.g. file 3 of 5 is
        // missing or the network fails), the helper must DELETE the already-uploaded files so
        // they do not accumulate as orphaned resources. The exception must still propagate.
        var uploadCount = 0;
        var deleted = new List<string>();
        using var handler = new HttpHandlerAssert(req =>
        {
            // DELETE first so we don't match the upload-collection /files path against this.
            if (req.Method == HttpMethod.Delete)
            {
                var segments = req.RequestUri!.AbsolutePath.Split('/');
                var fileId = segments[segments.Length - 1];
                deleted.Add(fileId);
                return MakeJsonResponse(FakeFileDeletedJson(fileId));
            }
            if (req.Method == HttpMethod.Post && req.RequestUri!.AbsolutePath.Contains("/files", StringComparison.Ordinal))
            {
                uploadCount++;
                if (uploadCount == 3)
                {
                    // 400 is non-retriable; the SDK retry policy ignores it. 5xx would trigger
                    // retries and confuse the assertion on upload count.
                    return new HttpResponseMessage(HttpStatusCode.BadRequest)
                    {
                        Content = new StringContent("{\"error\":{\"code\":\"BadRequest\",\"message\":\"upload-failed-on-3\"}}", Encoding.UTF8, "application/json"),
                    };
                }
                return MakeJsonResponse(FakeFileJson($"file_{uploadCount}"));
            }
            return MakeJsonResponse("{}");
        });

#pragma warning disable CA5399
        using var httpClient = new HttpClient(handler);
#pragma warning restore CA5399
        var projectClient = new AIProjectClient(
            new Uri("https://test.openai.azure.com/"),
            new FakeAuthenticationTokenProvider(),
            new AIProjectClientOptions { Transport = new HttpClientPipelineTransport(httpClient) });
        var chatClient = new FoundryChatClient(projectClient, "gpt-4o-mini");

        var paths = new[] { MakeTempFile("a"), MakeTempFile("b"), MakeTempFile("c"), MakeTempFile("d"), MakeTempFile("e") };
        try
        {
            await Assert.ThrowsAnyAsync<Exception>(() => chatClient.CreateVectorStoreAsync("knowledge-base", paths));

            // Three upload attempts: two succeeded, the third threw.
            Assert.Equal(3, uploadCount);
            // The two successful uploads must have been deleted as part of best-effort cleanup.
            Assert.Equal(2, deleted.Count);
            Assert.Contains("file_1", deleted);
            Assert.Contains("file_2", deleted);
        }
        finally
        {
            foreach (var p in paths)
            {
                File.Delete(p);
            }
        }
    }

    [Fact]
    public async Task CreateVectorStoreAsync_MidUploadFailure_CleanupSwallowsDeleteErrorsAsync()
    {
        // Q-B follow-on: if a cleanup DELETE itself fails, the helper must still propagate the
        // original upload exception — not the cleanup exception. The caller cares about the
        // upload failure; cleanup is best-effort.
        var uploadCount = 0;
        using var handler = new HttpHandlerAssert(req =>
        {
            if (req.Method == HttpMethod.Delete)
            {
                return new HttpResponseMessage(HttpStatusCode.BadRequest)
                {
                    Content = new StringContent("{\"error\":{\"code\":\"DeleteFailed\",\"message\":\"cleanup-failed\"}}", Encoding.UTF8, "application/json"),
                };
            }
            if (req.Method == HttpMethod.Post && req.RequestUri!.AbsolutePath.Contains("/files", StringComparison.Ordinal))
            {
                uploadCount++;
                if (uploadCount == 2)
                {
                    return new HttpResponseMessage(HttpStatusCode.BadRequest)
                    {
                        Content = new StringContent("{\"error\":{\"code\":\"BadRequest\",\"message\":\"upload-failed\"}}", Encoding.UTF8, "application/json"),
                    };
                }
                return MakeJsonResponse(FakeFileJson($"file_{uploadCount}"));
            }
            return MakeJsonResponse("{}");
        });

#pragma warning disable CA5399
        using var httpClient = new HttpClient(handler);
#pragma warning restore CA5399
        var projectClient = new AIProjectClient(
            new Uri("https://test.openai.azure.com/"),
            new FakeAuthenticationTokenProvider(),
            new AIProjectClientOptions { Transport = new HttpClientPipelineTransport(httpClient) });
        var chatClient = new FoundryChatClient(projectClient, "gpt-4o-mini");

        var paths = new[] { MakeTempFile("a"), MakeTempFile("b") };
        try
        {
            var ex = await Assert.ThrowsAnyAsync<Exception>(() => chatClient.CreateVectorStoreAsync("kb", paths));

            // The original upload-failure message must surface, not the cleanup-failure message.
            Assert.DoesNotContain("cleanup-failed", ex.Message ?? "", StringComparison.Ordinal);
        }
        finally
        {
            foreach (var p in paths)
            {
                File.Delete(p);
            }
        }
    }

    // ----- DeleteVectorStoreAsync -----

    [Fact]
    public async Task DeleteVectorStoreAsync_Mode1_CallsDeleteAsync()
    {
        var (chatClient, recorder) = CreateMode1(responseBody: FakeVectorStoreDeletedJson("vs_abc"));
        await chatClient.DeleteVectorStoreAsync("vs_abc");
        Assert.Contains(recorder.Requests, r => r.Method == "DELETE" && r.PathAndQuery.Contains("/vector_stores/vs_abc"));
    }

    [Fact]
    public async Task DeleteVectorStoreAsync_Mode2_CallsDeleteAsync()
    {
        var (chatClient, recorder) = CreateMode2(responseBody: FakeVectorStoreDeletedJson("vs_xyz"));
        await chatClient.DeleteVectorStoreAsync("vs_xyz");
        Assert.Contains(recorder.Requests, r => r.Method == "DELETE" && r.PathAndQuery.Contains("/vector_stores/vs_xyz"));
    }

    [Fact]
    public async Task DeleteVectorStoreAsync_NullId_ThrowsArgumentExceptionAsync()
    {
        var (chatClient, _) = CreateMode1();
        await Assert.ThrowsAnyAsync<ArgumentException>(() => chatClient.DeleteVectorStoreAsync(null!));
    }

    [Fact]
    public async Task DeleteVectorStoreAsync_HonorsCancellationAsync()
    {
        // Same approach as DeleteFileAsync_HonorsCancellationAsync — assert that the call
        // throws when the token is pre-cancelled, without asserting on the exact exception
        // surfaced by the SDK pipeline.
        var (chatClient, _) = CreateMode1(responseBody: FakeVectorStoreDeletedJson("vs_abc"));
        using var cts = new CancellationTokenSource();
        cts.Cancel();
        await Assert.ThrowsAnyAsync<Exception>(() => chatClient.DeleteVectorStoreAsync("vs_abc", cts.Token));
    }

    // ----- Fixtures and helpers -----

    private static HttpResponseMessage MakeJsonResponse(string json)
        => new(HttpStatusCode.OK)
        {
            Content = new StringContent(json, Encoding.UTF8, "application/json"),
        };

    private static string FakeFileJson(string id)
        => $"{{\"id\":\"{id}\",\"object\":\"file\",\"bytes\":11,\"created_at\":1700000000,\"filename\":\"x.txt\",\"purpose\":\"assistants\",\"status\":\"processed\"}}";

    private static string FakeFileDeletedJson(string id)
        => $"{{\"id\":\"{id}\",\"object\":\"file\",\"deleted\":true}}";

    private static string FakeVectorStoreJson(string id, string name)
        => FakeVectorStoreJsonWithStatus(id, name, status: "completed");

    private static string FakeVectorStoreJsonWithStatus(string id, string name, string status)
        => $"{{\"id\":\"{id}\",\"object\":\"vector_store\",\"created_at\":1700000000,\"name\":\"{name}\",\"usage_bytes\":0,\"file_counts\":{{\"in_progress\":0,\"completed\":0,\"failed\":0,\"cancelled\":0,\"total\":0}},\"status\":\"{status}\",\"last_active_at\":1700000000}}";

    private static string FakeVectorStoreDeletedJson(string id)
        => $"{{\"id\":\"{id}\",\"object\":\"vector_store.deleted\",\"deleted\":true}}";

    private sealed class RequestRecorder : HttpClientHandler
    {
        private readonly string _responseBody;
        public List<RecordedRequest> Requests { get; } = [];

        public RequestRecorder(string? responseBody)
        {
            this._responseBody = responseBody ?? "{}";
        }

        protected override async Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
        {
            this.Requests.Add(new RecordedRequest
            {
                Method = request.Method.Method,
                PathAndQuery = request.RequestUri?.PathAndQuery ?? "",
#if NET
                Body = request.Content is null ? "" : await request.Content.ReadAsStringAsync(cancellationToken).ConfigureAwait(false),
#else
                Body = request.Content is null ? "" : await request.Content.ReadAsStringAsync().ConfigureAwait(false),
#endif
            });
            return MakeJsonResponse(this._responseBody);
        }
    }

    private sealed class RecordedRequest
    {
        public string Method { get; set; } = "";
        public string PathAndQuery { get; set; } = "";
        public string Body { get; set; } = "";
    }
}
#pragma warning restore CS0618