fix: resolve perf issue with a lot of forms

[brvoisin]

The property TestResponse.forms takes time (about 1.6 seconds) on an HTML response containing a lot of forms (more than 30). For each form, the whole response is parsed. To avoid reparsing all the HTML, I added a cache on the property TestResponse.html that parse the response.

[brvoisin]

Hello!

You can reproduce with the attached HTML file 30forms_complex.html and the unit test below.

import time
from unittest import TestCase
from webtest import TestApp


def application(environ, start_response):
    with open("30forms_complex.html", "rb") as f:
        content = f.read()
    headers = [
        ("Content-Type", "text/html; charset=utf8"),
        ("Content-Length", str(len(content))),
    ]
    start_response("200 OK", headers)
    return [content]


class FormsTest(TestCase):
    def test_forms(self):
        app = TestApp(application)
        response = app.get("/")
        start = time.time()
        try:
            response.forms["form30"]
        finally:
            print("Time taken:", time.time() - start)

[brvoisin]

Thanks for your reactivity! It was released fast.