Easiest way to accept BTC and test
Blockchain.info service will not accept testnet coins so you can only test with regular coins.
As you can see in their site the minimum transfer amount allowed by their system is 0.0005 BTC so that's the minimum and no fee is required for that amount.

As you will be on the sender and receiving ends you can send any amount, if everything go as it should nothing will be lost.

On the other side I have heard about problems and delays using blockchain.info services, I don't know if they are fixed by now but probably if you are going to be using a bitcoin payment service usually you can go and check other commercial services out there.