Ideal serial communications test?
What exactly do you want to test?


the message handling (upper layers of your system)
the communication concept, including response timing, error handling, etc, or
the hardware layer concept, including cabling, reflexions, interference, variable number of nodes, etc
the specific configuration you are building (with or without external factors)


At some point these will all need testing, and will require different approaches. As you state "data corruption" as an important issue and you are talking about a specific setup I guess you mean the last bullet? In that case I would go for a combination of random testing and specifically testing the worst cases you can think of. (Random testing might indetify additional worst cases that you can identify and include explicitly.) Note that a realy thorough test would include establishing your margins, so you would need to vary for instance the driver's timing and supply voltage, the termination resistors, and the cable length. And then there's external factors...