function based wsgi container and return value bytes expected

[emattiza]

In going through the docs, i saw a snippet to test a wsgi container, and ran as-is in a fresh environment. What i encountered was an error related to the docs such that the return value did not encode to bytes to send as the output of the WSGI container rudimentary function. Specifically, in https://www.tornadoweb.org/en/stable/wsgi.html

import tornado
import tornado.wsgi
import tornado.httpserver
import tornado.ioloop

def simple_app(environ, start_response):
    status = "200 OK"
    response_headers = [("Content-type", "text/plain")]
    start_response(status, response_headers)
    return ["Hello world!\n"]

container = tornado.wsgi.WSGIContainer(simple_app)
http_server = tornado.httpserver.HTTPServer(container)
http_server.listen(8888)
tornado.ioloop.IOLoop.current().start()

The fix i applied was to change

return ["Hello world!\n"]

into

return ["Hello world!\n".encode("utf-8")]

Would a docs update suffice to contain this? Worth putting in a doc test? I would be a first time contributor here for the PR if so.

Thanks!

[bdarnell]

Yeah, looks like the docs should be updated (and making it a doctest would be nice). Personally I'd use return [b"Hello world!\n"] instead of explicitly encoding with utf8, even though that assumes that the source code encoding is utf8-compatible.

[emattiza]

I'll go with a byte literal then for the pr