Testing Process.Start?

Question

I am creating an application that manages multiple instances of an external utility, supplying each with data and fetching results.

But I'm facing a problem writing unit tests.

How to test if the target method actually starts a process (set via a property) when called?

I have tried:

• Make the class execute an external process and then use GetProcessesByName() to check if it has started.
• Use output redirection, e.g. using the greater-than sign to echo something to a file and test its existence

I feel like creating yet another .exe to test it is overkill.

Code:

public void Start() 
{
    if (!_isRunning) 
    {
        var startInfo = new ProcessStartInfo() {
          CreateNoWindow = true,
            UseShellExecute = true,

            FileName = _cmdLine,
            Arguments = _args
        };

        _process = Process.Start(startInfo);
        _isRunning = true;
    } 
    else 
    {
        throw new InvalidOperationException("Process already started");
    }
}

I want to unit-test it so that a new process should start if nothing is running (_isRunning == false).