Test Coverage for tornado app.

hello.py

import tornado.ioloop
import tornado.web

class MainHandler(tornado.web.RequestHandler):
    def get(self):
        self.set_status(400)
        self.write("Hello, world")

application = tornado.web.Application([
    (r"/", MainHandler),
])

if __name__ == "__main__":
    application.listen(8888)
    tornado.ioloop.IOLoop.instance().start()

requirements.txt

tornado==4.4.2
coverage==4.2

test_hello.py

import unittest

import tornado.ioloop
from tornado.httpclient import HTTPRequest
from tornado.testing import AsyncHTTPTestCase, gen_test

from hello import application

class SimpleTest(AsyncHTTPTestCase):
    def get_app(self):
        return application

    def get_new_ioloop(self):
        return tornado.ioloop.IOLoop.instance()

    @gen_test
    def test_bad_request(self):
        request = HTTPRequest(url=self.get_url('/'))
        with self.assertRaises(tornado.httpclient.HTTPError) as context:
            yield self.http_client.fetch(request)
        self.assertEqual(context.exception.code, 400)

if __name__ == "__main__":
    unittest.main(verbosity=2)
    # in cmdline run
    # coverage run --source=. --omit=env/* test_hello.py
    # coverage report