JAA License in none JAA states
 

Whilst in theory, having a professional JAR licence means that you could work in any JAA state, what about the other countries?

Is it the case that in a none JAA state, you have to ensure that you satisfy that country's regulations and take their tests etc? Or, do some accept JAA licences 'as is'. (Thinking about the theory too).

No specific countries in mind, just a general query.

You have to meet their individual requirements. If that allows a virtually like for like swap, then so much the better. As a minimum, you will probably have to do their air law exam(s).