Testing interactive ICommand in C#

I want to test some commands in my WPF project which contain user interaction needed parts.

This is the viewmodel:

class MainViewModel : ViewModelBase
{
    public ICommand Export { get; private set; }
    public MainViewModel()
    {
        Export = SynchronousCommand.Create((o) => ExportModel(o));
    }

    private void ExportModel(object parameter)
    {
        string exportPath = null;
        SaveFileDialog fileDialog = new SaveFileDialog();
        fileDialog.Filter = "UDPROJ (*.udproj) |*.udproj";
        if (fileDialog.ShowDialog() == true)
        {
            exportPath = fileDialog.FileName;
        }

        // Other logic which should run in test...
    }
}

So I want to call this Export command from a test project without calling the SaveFileDialog. My first idea was that I have to send some command parameters through parameter but I would like to ask you, is there a more elegant way (becuase I have to get the command parameters in every case where the command contains some dialog calling)?