protected override Task ExecuteAsync(CancellationToken stoppingToken)
        {
            var Scope = Factory.CreateScope();

            Client = Scope.ServiceProvider.GetRequiredService <ITestClient>();

            Console.WriteLine("Start Listening for Messages");

            Client.RegisterHandler(
                (message, token) =>
            {
                State.AddMessage(message);

                return(Task.CompletedTask);
            });

            return(Task.CompletedTask);
        }