def test_nonexistentPathEntry(self):
        """
        Test that getCache skips over any entries in a plugin package's
        C{__path__} which do not exist.
        """
        path = self.mktemp()
        self.assertFalse(os.path.exists(path))
        # Add the test directory to the plugins path
        self.module.__path__.append(path)
        try:
            plgs = list(plugin.getPlugins(ITestPlugin, self.module))
            self.assertEqual(len(plgs), 1)
        finally:
            self.module.__path__.remove(path)

        Test that getCache skips over any entries in a plugin package's
        C{__path__} which do not exist.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/test/test_plugin.py