RichardSzalay.MockHttp.WebSockets 0.1.0-pre1

Write blazing fast tests for ClientWebSocket with no abstractions. Real WebSockets, no network.

This repository is in early development phase. There are no official releases yet.

Raw WebSocket Usage

var cancellationToken = CancellationToken.None;

using var mockServer = MockWebSocketServer.ForEndpoint(async (ws, ct) =>
{
    // This is the 'server'. When it exits, the Websocket will shutdown.
    
    Memory<byte> buffer = new(new byte[4]);

    while (!ws.CloseStatus.HasValue)
    {
        var result = await ws.ReceiveAsync(buffer, ct);

        if (result.MessageType == WebSocketMessageType.Close)
        {
            continue;
        }

        var messageValue = int.Parse(buffer.Span.Slice(0, result.Count));
        
        var sendBytes = Encoding.UTF8.GetBytes((messageValue + 1).ToString(), buffer.Span);

        await ws.SendAsync(buffer.Slice(0, sendBytes), WebSocketMessageType.Binary, false, ct);
    }

    if (ws.State == WebSocketState.CloseReceived)
    {
        await ws.CloseAsync(ws.CloseStatus.Value, ws.CloseStatusDescription, ct);
    }
});

// This needs to be passed into ClientWebSocket.ConnectAsync
var messageInvoker = mockServer.ToMessageInvoker();

// Everything below is the 'client', so probably in your application code not your test

var client = new ClientWebSocket();
await client.ConnectAsync(new Uri("ws://localhost"), messageInvoker, cancellationToken);

int messageValue = 1;
Memory<byte> buffer = new(new byte[4]);

for (var i = 0; i < 10; i++)
{
    var bufferLength = Encoding.UTF8.GetBytes(messageValue.ToString(), buffer.Span);

    await client.SendAsync(buffer.Slice(0, bufferLength), WebSocketMessageType.Text, false,
        cancellationToken);

    var receiveResult = await client.ReceiveAsync(buffer, cancellationToken);

    messageValue = int.Parse(buffer.Span.Slice(0, receiveResult.Count));
}

await client.CloseAsync(WebSocketCloseStatus.NormalClosure, "Done", cancellationToken);

Client Mock Support

This library primarily focuses on mocking remote WebSocket servers in order to test ClientWebSocket code. The reverse is already possible using Microsoft.AspNetCore.Mvc.Testing, but can be supplemented by MockHttp.WebSocket's serialization helpers since they simply wrap WebSocket:

// Standard Microsoft.AspNetCore.Mvc.Testing stuff, no custom injection required
using var host = new WebApplicationFactory<Program>();
var webSocketClient = host.Server.CreateWebSocketClient();
var webSocket = await webSocketClient.ConnectAsync(new Uri(streamUrl!), CancellationToken.None);

var mockJsonClient = new JsonWebSocket(webSocket);

// Have at...