A Dumb Static HTTP server for unit testing (will serve up a directory for you)

gistfile1.cs

public sealed class StaticHttpServer : IDisposable
{
    public int Port { get; protected set; }
    public string RootPath { get; protected set; }
    
    IDisposable inner;

    public StaticHttpServer(int port, string rootPath)
    {
        Port = port; RootPath = rootPath;
    }

    public IDisposable Start()
    {
        if (inner != null) {
            throw new InvalidOperationException("Already started!");
        }

        var server = new HttpListener();
        server.Prefixes.Add(String.Format("http://+:{0}/", Port));
        server.Start();

        var listener = Observable.Defer(() => Observable.FromAsyncPattern<HttpListenerContext>(server.BeginGetContext, server.EndGetContext)())
            .Repeat()
            .Subscribe(ctx => {
                if (ctx.Request.HttpMethod != "GET") {
                    closeResponseWith(ctx, 400, "GETs only");
                    return;
                }

                var target = Path.Combine(RootPath, ctx.Request.Url.AbsolutePath.Replace('/', Path.DirectorySeparatorChar).Substring(1));
                var fi = new FileInfo(target);

                if (!fi.FullName.StartsWith(RootPath)) {
                    closeResponseWith(ctx, 401, "Not authorized");
                    return;
                }

                if (!fi.Exists) {
                    closeResponseWith(ctx, 404, "Not found");
                    return;
                }

                try {
                    using (var input = File.OpenRead(target)) {
                        ctx.Response.StatusCode = 200;
                        input.CopyTo(ctx.Response.OutputStream);
                        ctx.Response.Close();
                    }
                } catch (Exception ex) {
                    closeResponseWith(ctx, 500, ex.ToString());
                }
            });

        var ret = Disposable.Create(() => {
            listener.Dispose();
            server.Stop();
            inner = null;
        });

        inner = ret;
        return ret;
    }

    static void closeResponseWith(HttpListenerContext ctx, int statusCode, string message)
    {
        ctx.Response.StatusCode = statusCode;
        using (var sw = new StreamWriter(ctx.Response.OutputStream, Encoding.UTF8)) {
            sw.WriteLine(message);
        }
        ctx.Response.Close();
    }

    public void Dispose()
    {
        var toDispose = Interlocked.Exchange(ref inner, null);
        if (toDispose != null) {
            toDispose.Dispose();
        }
    }
}