def test_realpathSymlink(self):
        """
        L{FilePath.realpath} returns the path of the ultimate target of a
        symlink.
        """
        self.createLinks()
        self.symlink(self.path.child(b"file2.link").path,
                     self.path.child(b"link.link").path)
        self.assertEqual(self.path.child(b"link.link").realpath(),
                          self.path.child(b"sub1").child(b"file2"))

        L{FilePath.realpath} returns the path of the ultimate target of a
        symlink.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/test/test_paths.py