There is a message(text), which format and content i definitely know.
For now,class in Java,that parses and reads this message from file,is implemented.
Generally I agree with Eugene Kuleshov. But if you still need such mocking I'd suggest you to use BlckingQueue from java.util.concurent package. I think it is not a big problem to wrap it with javax.jms.Queue interface. BTW it is a good idea for some kind of open-source project.