Random port assignment doesn't work

[kbalonek]

I tried using the "Dynamic LiveServerTestCase port" feature as described in the docs. I am setting the LIVESERVER_PORT setting to 0 but the test server always falls back to flask default, port 5000. This failing python2 test case illustrates this:

from urllib2 import urlopen
from flask import Flask
from flask_testing import LiveServerTestCase

class MyTest(LiveServerTestCase):

    def create_app(self):
        app = Flask(__name__)
        app.config['TESTING'] = True
        # Default port is 5000
        app.config['LIVESERVER_PORT'] = 0
        # Default timeout is 5 seconds
        app.config['LIVESERVER_TIMEOUT'] = 10
        return app

    def test_server_doesnt_use_flask_default_port(self):
        self.assertNotEqual(self.get_server_url(), 'http://localhost:5000')