What would be handy, would be a serial port 'loopback' test.
I have either a dud ARF module or one of the Pi B+'s with a faulty serial port as my ARF fails to initialise. At the moment, don't know which but I suspect the ARF.
It may be handy to test if the Rx & Tx pins are shorted before setting up the ARF and if they are, pop up a message saying something like 'Serial Port test OK - Loopback or shorted data pins'. If it was deliberately shorted or looped back, then that confirms the Tx & Rx on the UART is working OK. If it's shorted and doesn't pop up the message, dud RPi. If the ARF is plugged in and working, then it just gives the ARF config messages. At the moment it's tricky to see where the issue is.
The instructions to test a Pi serial port are a bit convoluted, especially for someone who doesn't have a copy of the vanilla OS, requiring setting the console port off and installing and running something like Minicom.