Joey
I think that you are interested in USB so I will restrict to this.
The uTasker simulator (works with VisualStudio, which probably only works natively on Windows) can't hook to an real USB port of the PC since the PC has USB host and not device interfaces.This means that it uses scripts for USB development/testing as well as an integrated enumeration sequence that is executed when connecting to the USB-device.
This means that the standard USB enumeration sequence is played through the code (starting with the USB reset state interrupt, followed by the SETUP tokens setting an address, requesting strings, descriptors etc, - up to setting the configuration). This verifies that all data returned by the device/software is correct before showing that enumeration succeeded.
To subsequently test a class (and/or application) one creates test scripts which exercise standard test procedures (eg. a USB-MSD class script may request some sectors and write files to the FAT so that the software can be subjected to these standard USB communication procedures - for analysis, review, optimisation or debugging of particular cases). For example I have test scripts for typical Windows 8.1 and MAC OS X USB-MSD connections, file writes, deletes etc. since they work differently and this allows compatibility to be checked easily after code changes have been made.
[Side note: the USB scripts are created by taking recording from real USB operation - or particular good or bad cases - and using these as script inputs].
I don't know exactly what type of automated testing you are refering to. The uTasker simulator is designed to accelerate development and project maintenance, which includes efficient testing capabilities if this is what you are referring to.
Regards
Mark
P.S. The simulator generally allows (approx.) real-time interactions with the emulated Kinetis, which is demonstarted best based on its Ethernet capabilities:
http://www.utasker.com/docs/KINETIS/uTaskerV1.4_Kinetis.pdf
Kinetis: µTasker Kinetis support
For the complete "out-of-the-box" Kinetis experience and faster time to market