The 2-to-3 transition

While the 2-to-3 tool might be useful, it does not help get projects follow the recommended path of getting compatible prior to the actual transition. Many projects use a mixture of Python and C (or similar language) that requires considerable effort to first update API's before transitioning to Python 3. Thus, just getting 'python2.6 -3' to pass can require major changes to a project's code. You will still need extensive user testing to ensure that these changes are correct even if a project has extensive tests because those tests usually do not address language changes.