Nowadays, although python2 still are the production preferred choice, python3 is maturing and surely started taking over. Testing under python3 environment is pretty easy.

On Linux, most distros have both python2 and python3 bundled. However, on OSX, you need to install python3 by yourself. Fortunately, it is one command away with the magic of brew.

$ brew install python3

Then you could check by calling python3 if it works. Then you could make a virtuanenv with python3.

$ mkvirtualenv --python=`which python3` en-py3
(en-py3) $

That’s all. Nothing extra required. Happy testing your app on python3