Automated Java unit testing

I'm quite surprise by this product:

Parasoft Jtest® 7.0 with Test Case Sniffer?
Automates Java unit testing & code compliance. Auto-generates JUnit test cases from a running application. Tests individual classes or large, complex applications.

I can't see how a program can decide if a method that return false for example is the correct beheavior.
It can test if some part of the program throws exception but it seems to me it needs human interaction to decide which behavior is correct or not...