Hello M@he$h,
unfortunately, I can not tell you anything specific about WmTestSuite. I have asked our SAG consultants for a demo license multiple times, but never actually got anything from them.
As far as I understand it, WmTestSuite relies on developers to model the tests as Flow Services. But I don’t think this is a good idea, because in my opinion, complex logic should never be implemented using Flow Services, as they are slower and harder to debug than a simple JUnit/Java test. And you’ll get RSI from all the pointing and clicking 
So, I have decided to develop my own unit testing framework for Integration Server. It’s completely Open Source and you can test your services using POJOs instead of messing with IData. You can find the details and a short example in this forum post:
http://tech.forums.softwareag.com/techjforum/posts/list/0/24260.page#201190
Please let me know, if this helps you.
Best regards,
Stefan
#webMethods#Integration-Server-and-ESB