Teamup/tests/TeamUp.IntegrationTests/ModelClientToolTests.cs

using System.Net;
using System.Text;
using TeamUp.Modules.Integrations.Ai;
using TeamUp.SharedKernel.Ai;
using Xunit;

namespace TeamUp.IntegrationTests;

/// <summary>
/// The model-client tool-use plumbing: the OpenAI-compatible adapter serializes tools + a tool-use
/// conversation and parses tool calls out of the reply; the deterministic "tooluse" stub drives the
/// loop (ask for a tool, then answer once a result is present).
/// </summary>
public sealed class ModelClientToolTests
{
    [Fact]
    public async Task OpenAi_adapter_sends_tools_and_parses_tool_calls()
    {
        const string reply =
            """{"choices":[{"message":{"role":"assistant","content":null,"tool_calls":[{"id":"call_abc","type":"function","function":{"name":"search_issues","arguments":"{\"q\":\"bug\"}"}}]}}]}""";
        var handler = new CapturingHandler(reply);
        var client = new OpenAiCompatibleModelClient(new HttpClient(handler));

        var request = new ModelRequest(
            "openai", "gpt-4o", "sk-test", null, "find bugs", MaxTokens: 512,
            Tools: [new ModelTool("search_issues", "Search the tracker.", """{"type":"object"}""")],
            Messages: [new ModelMessage("user", "find bugs")]);

        var completion = await client.CompleteAsync(request);

        Assert.True(completion.Success);
        var call = Assert.Single(completion.ToolCalls!);
        Assert.Equal("call_abc", call.Id);
        Assert.Equal("search_issues", call.Name);
        Assert.Contains("bug", call.ArgumentsJson);

        // The outgoing body carries the tool definition and the conversation.
        Assert.Contains("\"tools\"", handler.LastBody);
        Assert.Contains("search_issues", handler.LastBody);
        Assert.Contains("find bugs", handler.LastBody);
    }

    [Fact]
    public async Task OpenAi_adapter_returns_plain_text_when_no_tool_calls()
    {
        const string reply = """{"choices":[{"message":{"role":"assistant","content":"Here are the bugs."}}]}""";
        var client = new OpenAiCompatibleModelClient(new HttpClient(new CapturingHandler(reply)));

        var completion = await client.CompleteAsync(new ModelRequest("openai", "gpt-4o", "sk", null, "hi"));

        Assert.True(completion.Success);
        Assert.Equal("Here are the bugs.", completion.Text);
        Assert.Null(completion.ToolCalls);
    }

    [Fact]
    public async Task ToolUse_stub_asks_for_a_tool_then_answers_once_a_result_is_present()
    {
        var stub = new ToolUseStubModelClient();
        List<ModelTool> tools = [new ModelTool("lookup", null, "{}")];

        var first = await stub.CompleteAsync(new ModelRequest(
            "tooluse", "m", "", null, "do it", Tools: tools, Messages: [new ModelMessage("user", "do it")]));
        var toolCall = Assert.Single(first.ToolCalls!);
        Assert.Equal("lookup", toolCall.Name);
        Assert.Null(first.Text);

        var second = await stub.CompleteAsync(new ModelRequest(
            "tooluse", "m", "", null, "do it", Tools: tools,
            Messages:
            [
                new ModelMessage("user", "do it"),
                new ModelMessage("assistant", null, first.ToolCalls),
                new ModelMessage("tool", "the result", ToolCallId: toolCall.Id),
            ]));

        Assert.Null(second.ToolCalls);
        Assert.Contains("do it", second.Text!);
    }

    private sealed class CapturingHandler(string responseJson) : HttpMessageHandler
    {
        public string LastBody { get; private set; } = string.Empty;

        protected override async Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
        {
            LastBody = await request.Content!.ReadAsStringAsync(cancellationToken);
            return new HttpResponseMessage(HttpStatusCode.OK)
            {
                Content = new StringContent(responseJson, Encoding.UTF8, "application/json"),
            };
        }
    }
}