def test_statNotExisting(self):
        """
        stat should fail with L{ftp.FileNotFoundError} on a file that doesn't
        exist.
        """
        d = self.shell.stat(('foo',), ('size', 'directory'))
        return self.assertFailure(d, ftp.FileNotFoundError)

        stat should fail with L{ftp.FileNotFoundError} on a file that doesn't
        exist.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/test/test_ftp.py