It seems that it is not possible any more to use the PyDev test runner for the latest version of Aptana studio (3.0.5) (containing Pydev v 2.2.2)
When running the unit tests, the following exception is through by the pydev-plugin: AttributeError: 'module' object has no attribute 'exc_clear' (Occurs in 'Aptana Studio 3\plugins\org.python.pydev.debug_2.2.2.2011100512\pysrc\runfiles.py", line 72, in main' : 'sys.exc_clear()')
I figured out that sys.exc_clear() is a Python-2 method that isn't supported any more by Python-3 ...
I don't know if pydev 2.2.3 fixes this problem ... but it is not available for Aptana yet ...
The question has been answered.
-> Waiting for fix in next stable release
-> Using nightly until fix available (thanks to Fabio for the hint)
Apatana 3.0.5 (or Eclipse) using Pydev 2.2.2: Unit-tests not working any more for Python 3?