Nadav Samet’s Blog

Lately I’ve started to write many unit tests for my secret turbogears project. My secret project, like many other web 2.0 applications, can have a lot of users logged in at the same time and the actions of one user can affect other users.

The current testing tools provided by TurboGears do not give “one obvious way” to test multi-user scenarios. I came up last week with a simple class that will emulate a browser session of a single user against a cherrypy server. Its only task is actually to keep track of the visit cookie. This is a simple example of how I use it:

def test_breaking_in():
    user = BrowserSession()
    user.goto('/directory/for/members')
    assert 'You must login' in user.response
    assert '403' in user.status
    user.goto('/login?username=thesamet&password=secret')
    user.goto('/directory/for/members')
    assert 'Welcome to the members area' in user.response

The BrowserSession object truly shines when your testcase includes two users (or more):

def test_object_lock():
    user1 = BrowserSession()
    user2 = BrowserSession()
    user1.goto('/login?username=user1&password=pass1')
    user2.goto('/login?username=user2&password=pass2')
    user1.goto('/edit?page=pagex')
    user2.goto('/edit?page=pagex')
    assert 'Page is locked by user1' in user2.response
    user1.goto('/edit?page=pagex')
    assert "page is locked by user1" not in user1.response

and no - my secret project is not another wiki. I later found it very convenient to put test methods inside a TestCase object rather than many individual test functions. One of the benefits is that you can factor out the repeating code of the logins that appear in many tests to the setUp() method. In each test method, we will have new and fresh sessions:

class TwoUsersTestCase(unittest.TestCase):
    def setUp(self):
        self.user1 = BrowserSession()
        self.user2 = BrowserSession()
        self.user1.goto('/login?username=user1&password=pass1')
        self.user2.goto('/login?username=user2&password=pass2')

class SendPrivateMessageTestCase(TwoUsersTestCase):
    def test_send_message(self):
        self.user1.goto('/chat/send?to=user2&text=hello')
        self.user2.goto('/chat/receive')
        assert 'hello' in self.user2.response

     def test_flood_detection(self):
         for x in xrange(100):
             self.user1.goto('/chat/send?to=user2&text=hello')
         self.user2.goto('/chat/receive')
         assert 'user1 kicked out (flooding)' in self.user2.response

Now I’ll share with you the BrowserSession code. Feel free to use it:

import cherrypy
from turbogears import testutil

def cookie_header(morsel):
    """Returns a dict containing cookie information to pass to a server."""
    return {'Cookie': morsel.output(header="")[1:]}

class BrowserSession(object):
    def __init__(self):
        self.cookie_name = turbogears.config.get(’visit.cookie.name’, ‘tg-visit’)
        self.visit = None
        self.response, self.status = None, None

    def goto(self, *args, **kwargs):
        if self.visit:
            headers = kwargs.get(’headers’, {})
            headers.update(cookie_header(self.visit))
            kwargs['headers'] = headers
        testutil.createRequest(*args, **kwargs)
        if self.cookie_name in cherrypy.response.simple_cookie:
            self.visit = cherrypy.response.simple_cookie[self.cookie_name]
        self.response = cherrypy.response.body[0]
        self.status = cherrypy.response.status

Ideas and suggestions are welcome!