old_contents: from subprocess import call, check_output
  
  class TestVenv:
      """ Test that virtualenvwrapper is installed
          a venv with Python 3 is ready"""
new_contents: from subprocess import call, check_output
  from locale import getpreferredencoding
  import sys
  
  class TestVenv:
      """ Test that virtualenvwrapper is installed
          a venv with Python 3 is ready"""
  
      def python_version(self):
          """ return version of python as obtained from python --version """
          output = check_output(['python', '--version']).decode(getpreferredencoding()).strip()
          return output
      
      def test_python_version(self):
          """ test if python is indeed 3.4.3 """
          assert self.python_version() == 'Python 3.4.3'
      
      def test_venv_activated(self):
          """ Test if the Python 3 environment is activated """
          assert hasattr(sys, 'real_prefix')
          
      
subject: Add tests for virtualenv