How do you manually trigger a KeyDown event onto a TextBox?

Hi,

I have a GUI program that I'd like to unit-test and I can't get anywhere with this event system.

I have a WinForms TextBox. I'd like to unit-test that, when I press 'Enter' while the TextBox has the focus, the contents of the TextBox are sent to the model.

How do you tell the TextBox that an event has occured ? (that must have been done somehow for it to work when live). Or is there another simpler solution to test that?

Thanks,

MrKoala