测试 Tornado 应用程序的 4xx 状态代码

Question

考虑以下 Tornado (v 4.0.2) 应用程序，它是官方hello world 示例的一点修改版本：

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()

如您所见，这里唯一的区别是set_status 调用MainHandler。现在，我将这段代码保存到app.py，然后我打开tests.py，然后我把这个简单的单元测试放在那里：

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

from app 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('/'))
        response = yield self.http_client.fetch(request)
        self.assertEqual(response.code, 400)

当我使用 python -m tornado.test.runtests tests 运行此测试时，我得到以下结果：

E
======================================================================
ERROR: test_bad_request (tests.SimpleTest)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/usr/local/lib/python2.7/dist-packages/tornado/testing.py", line 118, in __call__
    result = self.orig_method(*args, **kwargs)
  File "/usr/local/lib/python2.7/dist-packages/tornado/testing.py", line 494, in post_coroutine
    timeout=timeout)
  File "/usr/local/lib/python2.7/dist-packages/tornado/ioloop.py", line 418, in run_sync
    return future_cell[0].result()
  File "/usr/local/lib/python2.7/dist-packages/tornado/concurrent.py", line 109, in result
    raise_exc_info(self._exc_info)
  File "/usr/local/lib/python2.7/dist-packages/tornado/gen.py", line 631, in run
    yielded = self.gen.throw(*sys.exc_info())
  File "tests.py", line 18, in test_bad_request
    response = yield self.http_client.fetch(request)
  File "/usr/local/lib/python2.7/dist-packages/tornado/gen.py", line 628, in run
    value = future.result()
  File "/usr/local/lib/python2.7/dist-packages/tornado/concurrent.py", line 111, in result
    raise self._exception
HTTPError: HTTP 400: Bad Request

----------------------------------------------------------------------
Ran 1 test in 0.022s

FAILED (errors=1)
[E 140929 12:55:59 testing:687] FAIL

显然这是正确的，因为处理程序设置了 400 状态码。 但是我怎样才能针对这种情况测试我的应用程序呢？我认为 4xx 代码很有用，所以我不想放弃它们。但是我是 Tornado 的新手，我无法找到测试它们的方法。有吗？

Answer 1

试试这个：

    @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)

请参阅assertRaises 的文档。