text: # Copyright (c) 2011-2013 Simplistix Ltd
  # See license.txt for license details.
  
  from nose.plugins.skip import SkipTest
  
  try:
      from testfixtures.components import TestComponents
  except ImportError:  # pragma: no cover
      raise SkipTest('zope.component is not available')
  
  from mock import Mock, call
  from testfixtures import Replacer, compare
  from unittest import TestCase
  
  from warnings import catch_warnings
  
  
  class ComponentsTests(TestCase):
  
      def test_atexit(self):
          m = Mock()
          with Replacer() as r:
              r.replace('atexit.register', m.register)
  
              c = TestComponents()
  
              expected = [call.register(c.atexit)]
  
              compare(expected, m.mock_calls)
  
              with catch_warnings(record=True) as w:
                  c.atexit()
                  self.assertTrue(len(w), 1)
                  compare(str(w[0].message), (  # pragma: no branch
                      "TestComponents instances not uninstalled by shutdown!"
                      ))
  
              c.uninstall()
  
              compare(expected, m.mock_calls)
  
              # check re-running has no ill effects
              c.atexit()
  
              compare(expected, m.mock_calls)
  