title: How does setuptools installs test dependencies on python setup.py test command
body: <p>When I use the command <code>python setup.py test</code>, all of the <a href="https://python-packaging.readthedocs.io/en/latest/testing.html" rel="nofollow noreferrer">documentation</a> I've seen says setuptools will handle installing the testing dependencies. Where does it install them and are they deleted from the machine after the test suite runs? I've noticed none of the testing modules are actually installed into my virtual environment after this command completes.</p>
  
  <p>I understand it takes all of the modules in the <code>tests_require</code> list and installs them somewhere but I'm not sure where, what it does with them afterward and why it does this. Also, is there any way to pass arguments to the command without using flags, like with a config file or something?</p>