def test_findCheckerFactories(self):
        """
        L{strcred.findCheckerFactories} returns all available plugins.
        """
        availablePlugins = list(strcred.findCheckerFactories())
        for plg in plugin.getPlugins(strcred.ICheckerFactory):
            self.assertIn(plg, availablePlugins)

        L{strcred.findCheckerFactories} returns all available plugins.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/cred/test/test_strcred.py