title: Test installed Python package
body: <p>To test my Python package I run in the source directory:
  <code>python setup.py test</code></p>
  
  <p>If I understand correctly this tests the code in the source directory, not the installed package.</p>
  
  <p>How can I test if the installation was successful.
  Is it possible (or even common practice) to run the test suite on the installed packages?</p>