Hardware emulation

Is there a way to emulate hardware I/Os while developing my Arduino program. I would like to simulate a radial encoder for use with developing my program. Is there any way to do this?

If you have a second Arduino, you could program it to output pulses at whatever rate you wanted to.

Hmmm that is a pretty interesting idea. I am somewhat of a beginner. How would I figure out what sort of pulses to program to emulate a rotary encoder?

How would I figure out what sort of pulses to program to emulate a rotary encoder?

You'd get hold of the device's datasheet and look at the timing diagrams, which is what you'd have to do anyway if you were going to emulate it.