Monday, June 23, 2014

Getting django LiveServerTestCase working with selenium's remote webdriver on VirtualBox

Our group does our development on linux VMs, usually running on a Windows host.  We want our developers to be able to write selenium system tests to wrap some of our existing functionality before we start diving into some deep refactoring.

Most of the LiveServerTestCase documentation I have seen is for the case of django running locally and talking to selenium directly.  Getting an instance of django running a VM working with selenium running on the VM host required a few adjustments.

Start with a modern Django

LiveServerTestCase was introduced in Django 1.4.  We were on Django 1.3.  I tried using django-selenium, but had significant problems with their built in test server implementation not starting, not stopping, or crashing in strange ways.

I ended up upgrading our project from django 1.3 to 1.6.5.  For our large project this just took ~2 hours of fiddling.

Open/forward required ports

It's probably best to just turn off the iptables service when setting things up.  If you have selinux running, set it in permissive mode.

Add a line in your file to configure the port to use for the testserver used by LiveServerTestCase.


It's important that you use '' and not 'localhost' so that the port forwarding on VirtualBox works.  I'm using 8008 because it is one of the auxiliary http ports recognized by the selinux default configuration.

Then edit the settings of the VM in VirtualBox to forward port 8008 to some unused port on your local machine.  We're forwarding port 80 on the VM to 8888, so I forwarded this test port to 8889.

Serve up static files

We have apache serving static files at /static_assets/.

The test server is a python server, so we had to configure it to find and serve these static files.  In a test-specific settings file, I added:

    'default': {
        'ENGINE': 'django.db.backends.sqlite3',
        'NAME': 'fact_rdb',

if settings.DATABASES['default']['ENGINE'] == 'django.db.backends.sqlite3':
    import os
    from django.conf.urls.static import static
    STATIC_ASSETS_URL = "/static_assets/"
    STATIC_ASSETS_ROOT = os.path.join(settings.PROJECT_PATH, 'static_assets')
    urlpatterns += patterns('',
        url(r'^static_assets/.*$', 'myapp.views.serve_static_assets', name="static_assets_for_testing"),

The last line is the important one.  It redirects to a view described below.

The lines where I an editing "LOGIN_REQUIRED_URLS_EXCEPTIONS" exist because we are using a middleware to handle restricting access to certain urls.  You can see what that middleware looks like here.  Remove that line if you're not using that middleware.

I'm also configuring the tests to use an in-memory sqlite database.  I recommend that you use this if possible.  If you are using custom sql in your code, this may not be possible, but if you're justing using the ORM it should work just fine.  Running with an in memory database (in my experience) seems to take a couple seconds off the execution time of every test in your test suite.

The view that ties into the url in the code above and serves up the static assets is as follows:

import os
from mimetypes import guess_type
from django.http import HttpResponse
from django.core.servers.basehttp import FileWrapper

def serve_static_assets(request):
    # Take a url like /static_assets/path/to/file.js and create a path
    filename = "/path/to/static/dir" + request.path_info
    static_file = FileWrapper(open(filename, 'rb'))
    mimetype = guess_type(request.path_info, False)[0] or 'binary/octet-stream'
    response = HttpResponse(static_file, mimetype=mimetype)
    response['Content-Length'] = os.path.getsize(filename)
    return response

WARNING: This is not a secure way to serve static files.  Please do not use this for anything but testing.

Add setUpClass and tearDownClass methods to your test classes

The following sets up a web driver (available at "self.driver" in your test functions) connected to the driver on the host machine.


class myTest(LiveServerTestCase):

    def setUpClass(cls):
        cls.driver = webdriver.Remote(
            command_executor='http://%s:%s/wd/hub' %(SELENIUM_HOST, SELENIUM_PORT),
        super(LoginTest, cls).setUpClass()

    def tearDownClass(cls):
        super(LoginTest, cls).tearDownClass()

To connect to a server running on the host machine, use the following settings.


On virtualbox, the IP of the host machine is usually

Running your tests

You'll need to first start a selenium server running on the host machine.  If the selenium driver server isn't running there will be nothing for your selenium test runner to talk to.

To do this you'll need java and selenium installed.  Also, add the executables for any desired driver plugins (e.g. the chrome driver plugin) on your path.  Run the server with something like:

"C:\Program Files (x86)\Java\jre7\bin\java.exe" -jar selenium-server-standalone-2.33.0.jar

On the VM, run the command to test your application.  Something like:

python test --settings=custom_settings_file module.class.test_function

I hope that helped!

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