Running django tests with selenium in docker

Question

For executing tests I usually run a separate container with:

docker-compose run --rm web /bin/bash

Where web is a container with django. From a shell I execute py.test from time to time.

In order to be able to reach selenium from a container with django and to allow the browser from selenium container to reach django's liveserver I decided to use "net" parameter which allows containers to share net. So I added it to the yml:

selenium:
    image: selenium/standalone-firefox
    net: "container:web"

Unfortunately this does not work. I do not see 4444 port in my django container.

It only works if instead of net:"container:web" I specify an autogenerated container's name, like net:"container:project_web_run_1".

Also I tried instead of docker-compose run --rm .... use docker-compose up --no-deps changing command parameter to py.test functional_tests but that did not work either.

Is this the right of using selenium with containers?

Answer 1

For anyone running pytest, and possibly pytest-splinter (Selenium wrapper)

version: '3'
services:
  db:
    image: postgres
  django:
    build: .
    ports: 
      - "8000:8000"
    depends_on:
      - db
      - selenium
  selenium:
    image: selenium/standalone-firefox-debug:latest
    ports:
      - "4444:4444"   # Selenium
      - "5900:5900"   # VNC 

Define a conftest.py in your root directory to make these fixtures available to all your tests

import socket

import pytest
from pytest_django.live_server_helper import LiveServer


@pytest.fixture(scope='session')
def test_server() -> LiveServer:
    addr = socket.gethostbyname(socket.gethostname())
    server = LiveServer(addr)
    yield server
    server.stop()


@pytest.fixture(autouse=True, scope='function')
def _test_server_helper(request):
    """
    Configures test_server fixture so you don't have to mark
    tests with @pytest.mark.django_db
    """
    if "test_server" not in request.fixturenames:
        return

    request.getfixturevalue("transactional_db")


# Settings below here are exclusive to splinter,
# I'm just overriding the default browser fixture settings
# If you just use selenium, no worries, just take note of the remote url and use 
# it wherever you define your selenium browser

@pytest.fixture(scope='session')
def splinter_webdriver():
    return 'remote'

@pytest.fixture(scope='session')
def splinter_remote_url():
    return 'http://selenium:4444/wd/hub'

Don't forget to set ALLOWED_HOSTS in your config file:

if env('USE_DOCKER') == 'yes':
    import socket

    ALLOWED_HOSTS = [socket.gethostbyname(socket.gethostname())]

# or just
ALLOWED_HOSTS = ['*']

Then just test away!

from django.urls import reverse


def test_site_loads(browser, test_server):
    browser.visit(test_server.url + reverse('admin:index'))