def test_developmentPluginAvailability(self):
        """
        Plugins added in the development path should be loadable, even when
        the (now non-importable) system path contains its own idea of the
        list of plugins for a package.  Inversely, plugins added in the
        system path should not be available.
        """
        # Run 3 times: uncached, cached, and then cached again to make sure we
        # didn't overwrite / corrupt the cache on the cached try.
        for x in range(3):
            names = self.getAllPlugins()
            names.sort()
            self.assertEqual(names, ['app', 'dev'])

        Plugins added in the development path should be loadable, even when
        the (now non-importable) system path contains its own idea of the
        list of plugins for a package.  Inversely, plugins added in the
        system path should not be available.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/test/test_plugin.py