Currently the minimum scale is applied exclusive and the maximum scale exclusive.
One of the two must indeed be applied exclusive and the other one inclusive.
The maximum scale is inclusive when following SLD conventions.
Code that must be corrected:
(I fixed the code below on 19-Nov-15, the tests were wrong!
OLD: return (maxScale <= viewPort.getScale() && viewPort.getScale() < minScale);
FIXED: return (maxScale <= viewPort.getScale() && viewPort.getScale() > minScale);