How to use the mwparserfromhell.nodes.ExternalLink function in mwparserfromhell

def test_showtree(self):
        """test ExternalLink.__showtree__()"""
        output = []
        getter, marker = object(), object()
        get = lambda code: output.append((getter, code))
        mark = lambda: output.append(marker)
        node1 = ExternalLink(wraptext("http://example.com"), brackets=False)
        node2 = ExternalLink(wraptext("http://example.com"), wraptext("Link"))
        node1.__showtree__(output.append, get, mark)
        node2.__showtree__(output.append, get, mark)
        valid = [
            (getter, node1.url), "[", (getter, node2.url),
            (getter, node2.title), "]"]
        self.assertEqual(valid, output)

def test_title(self):
        """test getter/setter for the title attribute"""
        title = wraptext("Example!")
        node1 = ExternalLink(wraptext("http://example.com/"), brackets=False)
        node2 = ExternalLink(wraptext("http://example.com/"), title)
        self.assertIs(None, node1.title)
        self.assertIs(title, node2.title)
        node2.title = None
        self.assertIs(None, node2.title)
        node2.title = "My Website"
        self.assertWikicodeEqual(wraptext("My Website"), node2.title)

def test_children(self):
        """test ExternalLink.__children__()"""
        node1 = ExternalLink(wraptext("http://example.com/"), brackets=False)
        node2 = ExternalLink(wraptext("http://example.com/"),
                             wrap([Text("Example"), Text("Page")]))
        gen1 = node1.__children__()
        gen2 = node2.__children__()
        self.assertEqual(node1.url, next(gen1))
        self.assertEqual(node2.url, next(gen2))
        self.assertEqual(node2.title, next(gen2))
        self.assertRaises(StopIteration, next, gen1)
        self.assertRaises(StopIteration, next, gen2)

def test_unicode(self):
        """test ExternalLink.__unicode__()"""
        node = ExternalLink(wraptext("http://example.com/"), brackets=False)
        self.assertEqual("http://example.com/", str(node))
        node2 = ExternalLink(wraptext("http://example.com/"))
        self.assertEqual("[http://example.com/]", str(node2))
        node3 = ExternalLink(wraptext("http://example.com/"), wrap([]))
        self.assertEqual("[http://example.com/ ]", str(node3))
        node4 = ExternalLink(wraptext("http://example.com/"),
                             wraptext("Example Web Page"))
        self.assertEqual("[http://example.com/ Example Web Page]", str(node4))

def test_strip(self):
        """test ExternalLink.__strip__()"""
        node1 = ExternalLink(wraptext("http://example.com"), brackets=False)
        node2 = ExternalLink(wraptext("http://example.com"))
        node3 = ExternalLink(wraptext("http://example.com"), wrap([]))
        node4 = ExternalLink(wraptext("http://example.com"), wraptext("Link"))

        self.assertEqual("http://example.com", node1.__strip__())
        self.assertEqual(None, node2.__strip__())
        self.assertEqual(None, node3.__strip__())
        self.assertEqual("Link", node4.__strip__())

def test_brackets(self):
        """test getter/setter for the brackets attribute"""
        node1 = ExternalLink(wraptext("http://example.com/"), brackets=False)
        node2 = ExternalLink(wraptext("http://example.com/"), wraptext("Link"))
        self.assertFalse(node1.brackets)
        self.assertTrue(node2.brackets)
        node1.brackets = True
        node2.brackets = False
        self.assertTrue(node1.brackets)
        self.assertFalse(node2.brackets)
        self.assertEqual("[http://example.com/]", str(node1))
        self.assertEqual("http://example.com/", str(node2))

def test_url(self):
        """test getter/setter for the url attribute"""
        url = wraptext("http://example.com/")
        node1 = ExternalLink(url, brackets=False)
        node2 = ExternalLink(url, wraptext("Example"))
        self.assertIs(url, node1.url)
        self.assertIs(url, node2.url)
        node1.url = "mailto:héhehé@spam.com"
        node2.url = "mailto:héhehé@spam.com"
        self.assertWikicodeEqual(wraptext("mailto:héhehé@spam.com"), node1.url)
        self.assertWikicodeEqual(wraptext("mailto:héhehé@spam.com"), node2.url)

def test_external_link(self):
        """tests for building ExternalLink nodes"""
        tests = [
            ([tokens.ExternalLinkOpen(brackets=False),
              tokens.Text(text="http://example.com/"),
              tokens.ExternalLinkClose()],
             wrap([ExternalLink(wraptext("http://example.com/"),
                                brackets=False)])),

            ([tokens.ExternalLinkOpen(brackets=True),
              tokens.Text(text="http://example.com/"),
              tokens.ExternalLinkClose()],
             wrap([ExternalLink(wraptext("http://example.com/"))])),

            ([tokens.ExternalLinkOpen(brackets=True),
              tokens.Text(text="http://example.com/"),
              tokens.ExternalLinkSeparator(), tokens.ExternalLinkClose()],
             wrap([ExternalLink(wraptext("http://example.com/"), wrap([]))])),

            ([tokens.ExternalLinkOpen(brackets=True),
              tokens.Text(text="http://example.com/"),
              tokens.ExternalLinkSeparator(), tokens.Text(text="Example"),
              tokens.ExternalLinkClose()],
             wrap([ExternalLink(wraptext("http://example.com/"),
                                wraptext("Example"))])),

            ([tokens.ExternalLinkOpen(brackets=False),
              tokens.Text(text="http://example"), tokens.Text(text=".com/foo"),
              tokens.ExternalLinkClose()],

([tokens.ExternalLinkOpen(brackets=True),
              tokens.Text(text="http://example.com/"),
              tokens.ExternalLinkClose()],
             wrap([ExternalLink(wraptext("http://example.com/"))])),

            ([tokens.ExternalLinkOpen(brackets=True),
              tokens.Text(text="http://example.com/"),
              tokens.ExternalLinkSeparator(), tokens.ExternalLinkClose()],
             wrap([ExternalLink(wraptext("http://example.com/"), wrap([]))])),

            ([tokens.ExternalLinkOpen(brackets=True),
              tokens.Text(text="http://example.com/"),
              tokens.ExternalLinkSeparator(), tokens.Text(text="Example"),
              tokens.ExternalLinkClose()],
             wrap([ExternalLink(wraptext("http://example.com/"),
                                wraptext("Example"))])),

            ([tokens.ExternalLinkOpen(brackets=False),
              tokens.Text(text="http://example"), tokens.Text(text=".com/foo"),
              tokens.ExternalLinkClose()],
             wrap([ExternalLink(wraptext("http://example", ".com/foo"),
                                brackets=False)])),

            ([tokens.ExternalLinkOpen(brackets=True),
              tokens.Text(text="http://example"), tokens.Text(text=".com/foo"),
              tokens.ExternalLinkSeparator(), tokens.Text(text="Example"),
              tokens.Text(text=" Web Page"), tokens.ExternalLinkClose()],
             wrap([ExternalLink(wraptext("http://example", ".com/foo"),
                                wraptext("Example", " Web Page"))])),
        ]
        for test, valid in tests:

def _handle_external_link(self, token):
        """Handle when an external link is at the head of the tokens."""
        brackets, url = token.brackets, None
        self._push()
        while self._tokens:
            token = self._tokens.pop()
            if isinstance(token, tokens.ExternalLinkSeparator):
                url = self._pop()
                self._push()
            elif isinstance(token, tokens.ExternalLinkClose):
                if url is not None:
                    return ExternalLink(url, self._pop(), brackets)
                return ExternalLink(self._pop(), brackets=brackets)
            else:
                self._write(self._handle_token(token))
        raise ParserError("_handle_external_link() missed a close token")