For the moment cross-python-versions fixtures work only if the fixtures/tests are generated in Python 3.
This means that if you generate your fixtures in Python3, you would be able to test them in either Python 2 or 3 but if the fixtures are generated in Python 2 and try to run them in Python 3, you might see errors like UnicodeDecodeError among others when autounit tries to unpickle py2 objects.
For the moment cross-python-versions fixtures work only if the fixtures/tests are generated in Python 3. This means that if you generate your fixtures in Python3, you would be able to test them in either Python 2 or 3 but if the fixtures are generated in Python 2 and try to run them in Python 3, you might see errors like
UnicodeDecodeError
among others when autounit tries to unpickle py2 objects.