At least for the Windows PC (my domain), there are a multitude of programs available that will run a comprehensive test of as many components as is practical to check. Is something similar available for the RPi?
Not really since it's pretty hard to break a Pi (via software).
What I can think of right now:
- For memory:
memtester, can be installed using
sudo apt-get install memtester.
sudo memtester <amount of memory to test> <number of times to run test>
- For GPIO pins: http://wiringpi.com/the-gpio-utility/pin-test/
I think those are the only ones that need testing.
For everything else, I don't think they need testing. You'll know when the SD card is bad when you see corrupt files. For USB, just plug in something and see if it works. Ethernet won't work without USB, so there's a hint. For HDMI, sound, and composite, just use them and check if it works. Also, does the CPU really need a diagnostics run?