wwtools/mbproxy/tests/Mbproxy.Tests/Admin/SignalRFakes.cs

using System.Collections.Concurrent;
using System.Security.Claims;
using Mbproxy.Admin;
using Microsoft.AspNetCore.Http.Features;
using Microsoft.AspNetCore.SignalR;

namespace Mbproxy.Tests.Admin;

/// <summary>
/// Minimal hand-written test doubles for the SignalR surface <see cref="StatusHub"/>
/// and <see cref="StatusBroadcaster"/> touch. The project carries no mocking framework,
/// so these record just enough to assert behaviour.
/// </summary>
internal sealed class FakeHubCallerContext : HubCallerContext
{
    public FakeHubCallerContext(string connectionId) => ConnectionId = connectionId;

    public override string ConnectionId { get; }
    public override string? UserIdentifier => null;
    public override ClaimsPrincipal? User => null;
    public override IDictionary<object, object?> Items { get; } = new Dictionary<object, object?>();
    public override IFeatureCollection Features { get; } = new FeatureCollection();
    public override CancellationToken ConnectionAborted => CancellationToken.None;
    public override void Abort() { }
}

/// <summary>Records every group join so tests can assert membership changes.</summary>
internal sealed class FakeGroupManager : IGroupManager
{
    public List<(string ConnectionId, string Group)> Added { get; } = [];

    public Task AddToGroupAsync(string connectionId, string groupName, CancellationToken cancellationToken = default)
    {
        Added.Add((connectionId, groupName));
        return Task.CompletedTask;
    }

    // StatusHub.OnDisconnectedAsync never calls RemoveFromGroupAsync — SignalR removes a
    // disconnected connection from its groups implicitly. Nothing to record here.
    public Task RemoveFromGroupAsync(string connectionId, string groupName, CancellationToken cancellationToken = default)
        => Task.CompletedTask;
}

/// <summary>Records every push so <see cref="StatusBroadcaster"/> tests can assert routing.</summary>
internal sealed class FakeStatusPushSink : IStatusPushSink
{
    private readonly ConcurrentBag<StatusResponse> _fleet = [];
    private readonly ConcurrentBag<(string Plc, PlcDetailResponse Detail)> _plc = [];

    public IReadOnlyCollection<StatusResponse> FleetPushes => _fleet;
    public IReadOnlyCollection<(string Plc, PlcDetailResponse Detail)> PlcPushes => _plc;

    public Task PushFleetAsync(StatusResponse snapshot, CancellationToken ct)
    {
        _fleet.Add(snapshot);
        return Task.CompletedTask;
    }

    public Task PushPlcAsync(string plcName, PlcDetailResponse detail, CancellationToken ct)
    {
        _plc.Add((plcName, detail));
        return Task.CompletedTask;
    }
}

/// <summary>
/// An <see cref="IStatusPushSink"/> whose every push fails with an exception from the
/// supplied factory — used to prove <see cref="StatusBroadcaster.PushOnceAsync"/> swallows
/// a transport fault (and that its <c>when (ex is not OperationCanceledException)</c> filter
/// still lets a cancellation propagate).
/// </summary>
internal sealed class ThrowingStatusPushSink(Func<Exception> exceptionFactory) : IStatusPushSink
{
    public Task PushFleetAsync(StatusResponse snapshot, CancellationToken ct)
        => throw exceptionFactory();

    public Task PushPlcAsync(string plcName, PlcDetailResponse detail, CancellationToken ct)
        => throw exceptionFactory();
}