How can I test an interactive function in emacs?

I'm the maintainer of an Emacs package whose entire function is related to user interaction. Whenever I make a change to the code, I have to test it out manually to see if it works. It would be nice if I could do some automated testing, but I have no idea how to simulate user input in the way that would be required to do so. Is there any way to run an interactive function that will prompt the user and then respond to that prompt with simulated typing (including key combinations like C-j)?