LehrerApp/LehrerApp.Desktop.Tests/McpClientRegistrationServiceTests.cs

using System.Text.Json.Nodes;
using LehrerApp.Desktop.Services.Mcp;
using Xunit;

namespace LehrerApp.Desktop.Tests;

public sealed class McpClientRegistrationServiceTests : IDisposable
{
    private readonly string _directory = Path.Combine(Path.GetTempPath(), $"lehrerapp-mcpreg-tests-{Guid.NewGuid():N}");
    public McpClientRegistrationServiceTests() => Directory.CreateDirectory(_directory);
    public void Dispose() { if (Directory.Exists(_directory)) Directory.Delete(_directory, true); }

    private string ConfigPath => Path.Combine(_directory, "claude_desktop_config.json");

    private string BuildFakeBridge()
    {
        var bridgePath = Path.Combine(_directory, "LehrerApp.McpBridge.exe");
        File.WriteAllText(bridgePath, "fake");
        return bridgePath;
    }

    [Fact]
    public void Register_OhneBridgeDatei_LiefertFehlerUndSchreibtNichts()
    {
        var service = new McpClientRegistrationService(ConfigPath, Path.Combine(_directory, "fehlt.exe"));

        var result = service.Register();

        Assert.False(result.Success);
        Assert.False(File.Exists(ConfigPath));
    }

    [Fact]
    public void Register_OhneBestehendeKonfiguration_LegtDateiMitEintragAn()
    {
        var bridgePath = BuildFakeBridge();
        var service = new McpClientRegistrationService(ConfigPath, bridgePath);

        var result = service.Register();

        Assert.True(result.Success);
        Assert.True(service.IsRegistered());
        var root = JsonNode.Parse(File.ReadAllText(ConfigPath))!;
        Assert.Equal(bridgePath, root["mcpServers"]!["lehrerapp"]!["command"]!.GetValue<string>());
    }

    [Fact]
    public void Register_BestehendeKonfigurationMitAnderenServern_BleibtErhalten()
    {
        File.WriteAllText(ConfigPath, """{"mcpServers":{"andererServer":{"command":"foo"}},"globalShortcut":"Ctrl+X"}""");
        var bridgePath = BuildFakeBridge();
        var service = new McpClientRegistrationService(ConfigPath, bridgePath);

        var result = service.Register();

        Assert.True(result.Success);
        var root = JsonNode.Parse(File.ReadAllText(ConfigPath))!;
        Assert.Equal("foo", root["mcpServers"]!["andererServer"]!["command"]!.GetValue<string>());
        Assert.Equal("Ctrl+X", root["globalShortcut"]!.GetValue<string>());
        Assert.Equal(bridgePath, root["mcpServers"]!["lehrerapp"]!["command"]!.GetValue<string>());
    }

    [Fact]
    public void Register_KaputteBestehendeKonfiguration_WirdNichtUeberschrieben()
    {
        File.WriteAllText(ConfigPath, "{ das ist kein json");
        var bridgePath = BuildFakeBridge();
        var service = new McpClientRegistrationService(ConfigPath, bridgePath);

        var result = service.Register();

        Assert.False(result.Success);
        Assert.Equal("{ das ist kein json", File.ReadAllText(ConfigPath));
    }

    [Fact]
    public void Unregister_EntferntNurEigenenEintrag()
    {
        File.WriteAllText(ConfigPath, """{"mcpServers":{"andererServer":{"command":"foo"},"lehrerapp":{"command":"bar"}}}""");
        var service = new McpClientRegistrationService(ConfigPath, BuildFakeBridge());

        var result = service.Unregister();

        Assert.True(result.Success);
        Assert.False(service.IsRegistered());
        Assert.Contains("andererServer", File.ReadAllText(ConfigPath));
    }

    [Fact]
    public void IsRegistered_OhneDatei_IstFalse()
    {
        var service = new McpClientRegistrationService(ConfigPath, BuildFakeBridge());

        Assert.False(service.IsRegistered());
    }
}