Drummond certifies AS2 software products for interoperability. It does not test your AS2 connection. See who needs which, and how to verify your setup works.
Three free ways to test an AS2 connection: mendelson's public test server, a DIY OpenAS2 instance, and AS2 Certify's automated tester. What each validates and when to pick which.
AS2 has no loopback test: every real validation needs a counterparty. Here's why, what a partner-free test actually requires, and your options from DIY to hosted.