Intelligent Anesthesia Scheduling

A Recipe for Selenium Testing a Django Project Using PostgreSQL in Bitbucket Pipelines

Time Commitment: This recipe should take about 20 minutes to run through if you have an existing Bitbucket account and have Git, Python, and Firefox already installed.

Below is a recipe for building a basic Django Project that can be tested with Selenium in a BitBucket pipeline. We create a bare project that includes just the admin urls and app to keep this as barebones as possible. Once the scaffolding for testing is working locally and in the bitbucket pipeline, starting and testing a new app with custom models, urls, and views will be straightforward.

Written by Wesley Emeneker 2022-12-17. Email dev@physs.co.

Things you need to follow this recipe closely

1. A recent python installed (3.6 or later) with the venv module available. See References for the Python 3.11 I used.
2. Git
3. Firefox web browser. (Chrome and Edge are options, but the test in the recipe hard-codes Firefox)
4. A Bitbucket account with Pipeline execution turned on (free accounts get 50 free minutes per month as of 2022-12-17)
5. A terminal in Linux or Mac OS, or PowerShell in Windows
6. When you encounter things like this: <PASSWORD>, use a unique string that only you know

This recipe has 3 major gates. Each gate must be completed in order.

1. Make a BitBucket repository with a Django project that runs on your local computer
2. Make and run a Selenium test against the project
3. Create and run a pipeline config in Bitbucket with PostgreSQL

Gate 1: Make a Bitbucket repository with a running Django project

Make a BitBucket Git Repository for the project

Clone the empty repository

cd ~ # Use your home directory as the starting point
git clone git@bitbucket.org:<YOUR_PROJECT>/selenium_test.git

cd # Use your home directory as the starting point
git clone git@bitbucket.org:<YOUR_PROJECT>/selenium_test.git

Notes

If you clone with HTTPS instead of SSH, you may have to setup an App password to clone the repository

Create the environment for the repository

py -m venv selenium_test_env
selenium_test_env/Scripts/activate
pip install django pytest pytest-django selenium

python3 -m venv ~/selenium_test_env
source ~/selenium_test_env/bin/activate
pip3 install django pytest pytest-django selenium

Notes

This recipe uses python with venv and pip because it is the lowest common denominator. Conda, poetry, pipenv, virtualenv, etc. will all work well if you prefer them.

Create the project and superuser

Use django_admin for the username of the superuser. Choose a good password and save it. We need it later when adding the DJANGO_ADMIN_PASSWORD variable to BitBucket.

django-admin startproject selenium_project selenium_test
cd selenium_test
.\manage.py makemigrations
.\manage.py migrate
.\manage.py createsuperuser --username django_admin

django-admin startproject selenium_project ~/selenium_test
cd ~/selenium_test
./manage.py makemigrations
./manage.py migrate
./manage.py createsuperuser --username django_admin

Discussion

Later in the recipe, the password will be stored in an environment variable and we will store it as a secure variable in BitBucket.

Test that you can login to the app

.\manage.py runserver

./manage.py runserver

1. Open a browser and visit http://127.0.0.1:8000/admin
2. Login with the django_admin account created earlier
3. Stop the runserver. For Linux/Mac, press Ctrl+c. For Windows, either Ctrl+c or Ctrl+BREAK

Gate 2: Successfully make and run Selenium tests against the project

Create the data fixtures needed by Django tests

cd ~
cd selenium_test
New-Item -Path .\tests\tests_selenium\fixtures -Type Directory
.\manage.py dumpdata auth.User -o .\tests\tests_selenium\fixtures\users.json

cd ~
cd selenium_test
mkdir -p tests/tests_selenium/fixtures
./manage.py dumpdata auth.User -o tests/tests_selenium/fixtures/users.json

Discussion

Storing the user model data in a file of JSON makes it easy to pre-load data for the database we will use for local Selenium tests. Storing the data this way is not a security risk. The passwords are not plaintext. That said, the password used for the django_admin account should not be reused anywhere else, and it definitely shouldn't be your production password.

Make the test

import os
from pathlib import Path

from django.test.selenium import SeleniumTestCase
from django.contrib.staticfiles.testing import StaticLiveServerTestCase
from selenium.webdriver.common.by import By

fixtures_directory = Path(__file__).parent / "fixtures"

"""
We MUST use a live server AND a transactional database for 2 reasons
1. If live_server is missing, the selenium webdriver won't be able to 
     actually receive any rendered page
2. If transactional_db is missing, all the app data will be kept in 
     memory in the test runner process, so the selenium process won't
     be able to access any of the data. 
   We must have a live database for this to work.
"""

class SeleniumTest(SeleniumTestCase, StaticLiveServerTestCase):
    databases = {"default"}
    fixtures = [
	fixtures_directory / "users.json",
    ]
    # browser and implicit_wait are needed by the SeleniumTestCase class
    # You can use 'chrome' or 'edge' here if you don't want to install firefox.
    browser = 'firefox'
    # Increasing the implicit_wait from the default of 3 makes the pipeline reliable
    implicit_wait = 10  
    # The SELENIUM_HOST variable may be defined by our bitbucket
    #   repository settings for using the selenium docker image.
    selenium_hub = None if not os.environ.get(
      "SELENIUM_HOST", None
    ) else f'http://{os.environ["SELENIUM_HOST"]}:{os.environ.get("SELENIUM_PORT", 4444)}'
    external_host = os.environ.get("SELENIUM_HOST", None)

    def tearDown(self):
        self.selenium.close()

    def test_login(self):
        login_button_xpath='//input[@value="Log in"]'
        self.selenium.get(f"{self.live_server_url}/admin")
        username_input = self.selenium.find_element(By.NAME, "username")
        username_input.send_keys('django_admin')
        password_input = self.selenium.find_element(By.NAME, "password")
        password_input.send_keys(os.environ["DJANGO_ADMIN_PASSWORD"])
        self.selenium.find_element(By.XPATH, login_button_xpath).click()

Successfully run the test from the selenium_test top-level directory

cd $HOME\selenium_test
$env:DJANGO_SETTINGS_MODULE='selenium_project.settings'
$env:DJANGO_ADMIN_PASSWORD='<THE PASSWORD>'
pytest

cd ~/selenium_test
export DJANGO_SETTINGS_MODULE="selenium_project.settings"
export DJANGO_ADMIN_PASSWORD="<THE PASSWORD>"
pytest

Notes

The first time this is run, the browser may take a long time to start (20-30 seconds).

Add, commit, and push

git add manage.py
git add selenium_project/wsgi.py selenium_project/urls.py \
    selenium_project/asgi.py selenium_project/__init__.py
git add tests/tests_selenium/fixtures/users.json \
    tests/tests_selenium/test_selenium_testapp_login.py
git commit -m "Ran the first successful Selenium test of selenium_testapp with Firefox"
git push

Discussion

~/selenium_test
├── db.sqlite3  # './manage migrate' created this sqlite3 db
├── geckodriver.log  # This log file was created by selenium
├── manage.py
├── selenium_project
│   ├── asgi.py
│   ├── __init__.py
│   ├── settings.py
│   ├── urls.py
│   └── wsgi.py
└── tests
    └── tests_selenium
	├── fixtures
	│   └── users.json
	└── test_selenium_testapp_login.py
	

Gate 3: Setting up a pipeline config to run in Bitbucket with PostgreSQL

All of the above steps must be successfully completed before moving on.

Make a settings.py for Bitbucket

Copy-Item .\selenium_project\settings.py .\selenium_project\settings.bitbucket-pipelines.py

cp selenium_project/settings.py selenium_project/settings.bitbucket-pipelines.py

DATABASES = {
    'default': {
	'ENGINE': 'django.db.backends.postgresql',
	'NAME': 'django',
	"USER": 'django',
	"PASSWORD": '<RECIPE_PASSWORD2>',
	'HOST': '127.0.0.1',
	"TEST": {
	    "NAME": 'django_test',
	}
    }
}

Discussion

The original settings.py uses a SQLite database definition that doesn't require a username and password. SQLite is a great choice for starting development. This recipe uses PostgreSQL in the pipeline because Bitbucket makes it easy to add and use services from docker images. This way, we get quick local development and quick pipeline work.

Make a bitbucket-pipelines.yml

Put the following code into bitbucket-pipelines.yml. Make certain that the POSTGRES DB, USER, and PASSWORD variables match the NAME, USER, and PASSWORD from selenium_project/settings.bitbucket-pipelines.py.

pipelines:
  default:
    - step:
        name: "Python 3.10 tests"
        image: python:3.10
        services:
          - postgresql14
          - selenium-firefox
        script:
          - pip install django pytest pytest-django selenium psycopg2
          - cp selenium_project/settings.bitbucket-pipelines.py selenium_project/settings.py
          - DJANGO_SETTINGS_MODULE="selenium_project.settings" pytest

definitions:
  services:
    postgresql14:
      image: postgres:14
      variables:
        POSTGRES_DB: 'django'
        POSTGRES_USER: 'django'
        POSTGRES_PASSWORD: '<RECIPE_PASSWORD2>'
        POSTGRES_DB_TEST: 'django_test'
    selenium-firefox:
      image: selenium/standalone-firefox:latest
      ports:
        - "4444:4444"

Add those files and push the changes to Bitbucket

cd
cd selenium_test
git add bitbucket-pipelines.yml selenium_project/settings.bitbucket-pipelines.py
git commit -m "Added bitbucket pipeline definition and Django project settings to match the pipeline configuration"
git push

The repository should now have these files:

~/selenium_test
├── bitbucket-pipelines.yml
├── db.sqlite3
├── geckodriver.log
├── manage.py
├── selenium_project
│   ├── asgi.py
│   ├── __init__.py
│   ├── settings.bitbucket-pipelines.py
│   ├── settings.py  # This file should NOT be in the git repository
│   ├── urls.py
│   └── wsgi.py
└── tests
    └── tests_selenium
	├── fixtures
	│   └── users.json
	└── test_selenium_testapp_login.py

Enable Pipelines for the Bitbucket Repository

Set the repository variables needed for the Selenium tests

1. In the Bitbucket repository, click Repository settings.
2. Under the "Pipelines" section, click Repository variables.
3. Add name "SELENIUM_HOST" value "127.0.0.1" uncheck the "secured" checkbox.
4. Add name "SELENIUM_PORT" value "4444" uncheck the "secured" checkbox.
5. Add name "DJANGO_ADMIN_PASSWORD" with the value of the django_admin superuser password chosen in Gate 1; check the "secured" checkbok

The SELENIUM_PORT variable must match the port definition in the selenium-firefox services section of bitbucket-pipelines.yml If you don't set the SELENIUM_HOST and SELENIUM_PORT repository variables correctly, there will be build errors like this: selenium.common.exceptions.SessionNotCreatedException: Message: Expected browser binary location, but unable to find binary in default location, no 'moz:firefoxOptions.binary' capability provided ...

Run the first pipeline

Wait for build success

Next Steps: Left for the reader

• If you don't have firefox installed or don't want to have it, use chrome or edge. This will required changing the browser variable in the unit test, and will require modifications to the bitbucket-pipelines.yml file to use a Chrome or Edge service
• Add an app, models, and urls and selenium tests starting from the unit testing template in test_selenium_testapp_login.py

Notes

References

• Bitbucket
• Selenium
• Python 3.11 for Windows
• Python 3.11 for MacOS
• Clone a Bitbucket Repository
• Ubuntu 22.04 python: sudo apt install python3 python3-venv