def test_doubleSlash(self):
        """
        Calling L{urlpath.URLPath.click} on a L{urlpath.URLPath} with a
        trailing slash with a relative URL containing a leading slash will
        result in a URL with a single slash at the start of the path portion.
        """
        self.assertEqual(
            str(self.path.click(b"/hello/world")).encode("ascii"),
            b"http://example.com/hello/world"
        )

        Calling L{urlpath.URLPath.click} on a L{urlpath.URLPath} with a
        trailing slash with a relative URL containing a leading slash will
        result in a URL with a single slash at the start of the path portion.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/python/test/test_urlpath.py