CPE testing tool

In our homes we could find many models of devices provided by Internet operators. They have diferent type of ports, features and Internet connection methods.
Lots of Internet providers lent this devices for customers and give it to another one if previous resign.
From operator point of view problem begins when he should test this device before giving it to the next customer. He needs to make testing procedure and aplication with implements it. But what he should do if he has 10, 20, 30 different type of modems, and doesn't want to provide dozens of applications ?
Presentation will describe methodology of creating testing tools that can be used with variety type of modems and routers.