public async void KillProcesses()
        {
            ICollection <Process> testProcesses = SpawnTestProcesses(2);

            testProcesses.Should().NotContain(process => process.HasExited, "haven't killed anything yet");

            await processKiller.DisableProcesses(cancellationTokenSource.Token);

            testProcesses.Should().OnlyContain(process => process.HasExited, "all processes should have been killed");
        }